GroupBox WINAPI

#include <stdio.h>
#include <windows.h>
char ClassName[] = "ClassName";
HWND test56;
HWND ndat;
LRESULT CALLBACK Windowpr(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hThisInstance,HINSTANCE hPrevInstance,LPSTR lpszArgument,int nFunsterStil)
{
    WNDCLASSEX t,t5;
    HWND t2,t6;
    MSG t3;
    t.cbSize = sizeof(WNDCLASSEX);
    t.cbWndExtra = 0;
    t.cbClsExtra = 0;
    t.lpfnWndProc = Windowpr;
    t.lpszClassName = ClassName;
    t.lpszMenuName = NULL;
    t.hIcon = LoadIcon(NULL,IDI_APPLICATION);
    t.hIconSm = LoadIcon(NULL,IDI_APPLICATION);
    t.hCursor = LoadCursor(NULL,IDC_ARROW);
    t.hInstance = hThisInstance;
    t.hbrBackground = (HBRUSH)(7);
    if (!RegisterClassEx(&t)){
        printf("Error Ocurred 0001\n");
        return -1;
    }
    t2 = CreateWindowEx(0,ClassName,"My title",WS_OVERLAPPEDWINDOW,0,0,300,300,NULL,NULL,NULL,NULL);
    if (t2 == NULL){
        printf("Error Ocurred 0002\n");
        MessageBox(NULL,"Error Ocurred 0002","Error",MB_ICONERROR);
        return -1;
    }
    ShowWindow(t2,nFunsterStil);
    while(GetMessage(&t3,NULL,0,0) > 0){
        TranslateMessage(&t3);
        DispatchMessage(&t3);
    }
    return 0;
}

LRESULT CALLBACK Windowpr(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam){
    switch(message){
        case WM_CREATE:
            test56 = CreateWindow("button",NULL,WS_CHILD | WS_VISIBLE | BS_GROUPBOX,4,4,130,130,hwnd,NULL,NULL,NULL);
            test56 = hwnd;
            ndat = CreateWindow("button","TESTING",WS_CHILD | WS_VISIBLE | WS_BORDER | BS_CENTER,40,65,60,30,test56,(HMENU)45,NULL,NULL);
            break;
        case WM_COMMAND:
            if (LOWORD(wparam) == 45){
                printf("Pressed button inside of groupbox :)\n");
            }
            break;
        case WM_CLOSE:
            DestroyWindow(hwnd);
            break;
        case WM_DESTROY:
            PostQuitMessage(0);
            break;
        default:
            DefWindowProc(hwnd,message,wparam,lparam);
            break;
    }
}