not work(TicTacToe)

import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;


public class TicTacToe extends Applet implements ActionListener {

/**
     *
     */
    private static final long serialVersionUID = 1831218949168974884L;
/**
     *
     */

Button squares[];
Button newGameButton;
Label score;
int emptySquaresLeft=9;

    public void init(){
        //add manager location applet, font and color
        this.setLayout(new BorderLayout());
        this.setBackground(Color.CYAN);

        //change font applet on bold and had size 20
        Font appletFont = new Font("Monospased", Font.BOLD, 20);
        this.setFont(appletFont);

        //create button "NewGame" and register it action listener

        newGameButton = new Button("new game");
        newGameButton.addActionListener(this);

        Panel topPanel = new Panel();
        topPanel.add(newGameButton);

            this.add(topPanel, "North");

            Panel centerPanel = new Panel();
            centerPanel.setLayout(new GridLayout(3,3));
            this.add(centerPanel, "Center");

            score = new Label("You turn");
            this.add(score, "South");

        //create massive for store links on 9 buttons

            squares = new Button[9];

        //create buttons, save links on massive, register them action listner,
        //color it in orange and add on panel

            for(int i=0;i<9;i++){
                squares[i] = new Button();
                squares[i].addActionListener(this);
                squares[i].setBackground(Color.ORANGE);
                centerPanel.add(squares[i]);
            }

    }

    public void actionPerfomed(ActionEvent e){
        Button theButton = (Button) e.getSource();

        //it button NewGame?
        if(theButton == newGameButton){
            for(int i=0;i<9;i++){
                squares[i].setEnabled(true);
                squares[i].setLabel("");
                squares[i].setBackground(Color.ORANGE);

            }

            emptySquaresLeft=9;
            score.setText("You turn!");
            newGameButton.setEnabled(false);

            return; //exit method
        }

        String winner = "";
        //it one of cells?

        for(int i=0;i<9;i++){
            if (theButton == squares[i]){
                squares[i].setLabel("X");
                winner = lookForWinner();

                if(!"".equals(winner)){
                    endTheGame();
                }else{
                    computerMove();
                    winner = lookForWinner();

                    if(!"".equals(winner)){
                        endTheGame();
                    }
                }
                break;
            }
        } //end of for

        if(winner.equals("X")){
            score.setText("You won");
        }else if(winner.equals("O")){
            score.setText("lost");
        }else if (winner.equals("T")){
            score.setText("its a tie");
        }
    }//end action perfomed method

/*this method call after move, for know who is winner.
 *he checks each rows,  for find same cell.
 * @retErn "X", "O", "T" - tie. "" - no winner
*/
    String lookForWinner(){
        String theWinner = "";
        emptySquaresLeft--;

        if(emptySquaresLeft==0){
            return "T"; //tie
        }

    //cheek row 1 - massive elements 0,1,2
    if(!squares[0].getLabel().equals("") &&
        squares[0].getLabel().equals(squares[1].getLabel()) &&
        squares[0].getLabel().equals(squares[2].getLabel())){
            theWinner = squares[0].getLabel();
            highlightWinnrer(0,1,2);
    //chek row 2 - massive elements 3,4,5
    }else if(!squares[3].getLabel().equals("") &&
        squares[3].getLabel().equals(squares[4].getLabel()) &&
        squares[3].getLabel().equals(squares[5].getLabel())){
            theWinner = squares[3].getLabel();
            highlightWinnrer(3,4,5);
    }else if(!squares[6].getLabel().equals("") &&
            squares[6].getLabel().equals(squares[7].getLabel()) &&
            squares[6].getLabel().equals(squares[8].getLabel() )) {
                theWinner = squares[6].getLabel();
                highlightWinnrer(6,7,8);
    }else if(!squares[0].getLabel().equals("") &&
            squares[0].getLabel().equals(squares[3].getLabel()) &&
            squares[0].getLabel().equals(squares[6].getLabel())){
                theWinner = squares[0].getLabel();
                highlightWinnrer(0,3,6);
    }else if(!squares[1].getLabel().equals("") &&
            squares[1].getLabel().equals(squares[4].getLabel()) &&
            squares[1].getLabel().equals(squares[7].getLabel())){
                theWinner = squares[1].getLabel();
                highlightWinnrer(1,4,7);
    }else if(!squares[2].getLabel().equals("") &&
            squares[2].getLabel().equals(squares[5].getLabel()) &&
            squares[2].getLabel().equals(squares[8].getLabel())){
                theWinner = squares[2].getLabel();
                highlightWinnrer(2,5,8);
    }else if(!squares[0].getLabel().equals("") &&
            squares[0].getLabel().equals(squares[4].getLabel()) &&
            squares[0].getLabel().equals(squares[8].getLabel())){
                theWinner = squares[0].getLabel();
                highlightWinnrer(0,4,8);
    }else if(!squares[2].getLabel().equals("") &&
            squares[2].getLabel().equals(squares[4].getLabel()) &&
            squares[2].getLabel().equals(squares[6].getLabel())){
                theWinner = squares[2].getLabel();
                highlightWinnrer(2,4,6);
    }
    return theWinner;

}

/**
 * this method applies set of rules, for look best computer move
 * if best move didn't find, selected a random cell.
 */
    void computerMove(){
        int selectedSquare;

        //at first computer try find empty cell beside
        //2 zero's, for victory.
        selectedSquare = findEmptySquare("O");

        //if he can't find two zero, then at last try not to give opponent
        //make row of 3 crosses, placing zero beside crosses
        if(selectedSquare == -1){
            selectedSquare = findEmptySquare("X");
        }

        //if selectedSquare == -1, then try take center cell
        if((selectedSquare == -1) && (squares[4].getLabel().equals("")) ){
            selectedSquare = 4;
        }
        //didn't luck with central cell, take a random
        if(selectedSquare == -1){
            selectedSquare = getRandomSquare();
        }
        squares[selectedSquare].setLabel("O");
    }

/**
 * this method cheek all row, column and diagonal for know, whether it two cells
 * with a both inscriptions and empty cell.
 * @param give X - for user and O - for computer
 * @return the number of free cells, or -1 if didn't find two cell with same inscription
 */
    int findEmptySquare(String player){
        int weight[] = new int[9];

        for( int i=0; i<9; i++){
            if(squares[i].getLabel().equals("O") )
                weight[i] = -1;
            else if (squares[i].getLabel().equals("X") )
                weight[i] = 1;
            else
                weight[i] = 0;
        }

        int twoWeights = player.equals("O") ? -2 : 2;

        //cheek if in first row two identical and one empty cell

        if(weight[0] + weight[1] + weight[2] == twoWeights){
            if(weight[0] == 0)
                return 0;
            else if (weight[1] == 0)
                return 1;
            else
                return 2;
        }

        //cheek if in two row two identical and one empty cell
        if(weight[3] + weight[4] + weight[5] == twoWeights){
            if(weight[3] == 0)
                return 3;
            else if (weight[4] == 0)
                return 4;
            else
                return 5;
        }
        //and row three
        if(weight[6] + weight[7] + weight[8] == twoWeights){
            if(weight[6] == 0)
                return 6;
            else if (weight[7] == 0)
                return 7;
            else
                return 8;
        }
        //now column 1
        if(weight[0] + weight[3] + weight[6] == twoWeights){
            if(weight[0] == 0)
                return 0;
            else if (weight[3] == 0)
                return 3;
            else
                return 6;
        }
        //column 2
        if(weight[1] + weight[4] + weight[7] == twoWeights){
            if(weight[1] == 0)
                return 1;
            else if (weight[4] == 0)
                return 4;
            else
                return 7;
        }
        //and 3
        if(weight[2] + weight[5] + weight[8] == twoWeights){
            if(weight[2] == 0)
                return 2;
            else if (weight[5] == 0)
                return 5;
            else
                return 8;
        }
        //now diagonal

        if(weight[0] + weight[4] + weight[8] == twoWeights){
            if(weight[0] == 0)
                return 0;
            else if (weight[4] == 0)
                return 4;
            else
                return 8;
        }

        //and two diagonal
        if(weight[2] + weight[4] + weight[6] == twoWeights){
            if(weight[2] == 0)
                return 2;
            else if (weight[4] == 0)
                return 4;
            else
                return 6;
        }
        //didn't find two identical cells
        return -1;

    }//end findEmptySquare();

    int getRandomSquare(){

        boolean gotEmptySquare = false;

        int selectedSquare = -1;

        do{
            selectedSquare = (int) (Math.random()*9);

            if(squares[selectedSquare].getLabel().equals("")){
                gotEmptySquare = true; //for finish cycle
            }
        } while (!gotEmptySquare);

        return selectedSquare;
    }//end getRandom method

/**
 * method selected winning line.
 * @param 1,2,3 cells for release
 */

    void highlightWinnrer(int win1, int win2, int win3){
        squares[win1].setBackground(Color.CYAN);
        squares[win2].setBackground(Color.CYAN);
        squares[win3].setBackground(Color.CYAN);
    }
    //after game all cells freeze. button "new game" - enabled;
    void endTheGame(){
        newGameButton.setEnabled(true);

        for(int i=0;i<9;i++){
            squares[i].setEnabled(false);
        }
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub

    }

}//end