@@IDENTITY after INSERT statement always returns 0

public int ExecuteInsertStatement(string statement)
    {
        InitializeAndOpenConnection();
        int id = -1;


        IDbCommand cmdInsert = connection.CreateCommand();
        cmdInsert.CommandText = statement;
        int rows = cmdInsert.ExecuteNonQuery();

        if (rows == 1)
        {
            IDbCommand cmdId = connection.CreateCommand();
            cmdId.CommandText = "SELECT @@Identity;";
            id = (int)cmdId.ExecuteScalar();
        }

        return id;
    }
    private void InitializeAndOpenConnection()
    {
        if (connection == null)
            connection = OleDbProviderFactory.Instance.CreateConnection(connectString);

        if(connection.State != ConnectionState.Open)
            connection.Open();
    }

public int ExecuteInsertStatement(string statement, string tableName)
    {
        InitializeAndOpenConnection();
        int id = -1;
        IDbCommand cmdInsert = connection.CreateCommand();
        cmdInsert.CommandText = statement + ";SELECT OID FROM " + tableName + " WHERE OID = SCOPE_IDENTITY();";
        id = (int)cmdInsert.ExecuteScalar();

        return id;
    }

SELECT SCOPE_IDENTITY()

public int ExecuteInsertStatement(string statement)
{
    InitializeAndOpenConnection();

    IDbCommand cmdInsert = connection.CreateCommand();
    cmdInsert.CommandText = statement + "; SELECT @@Identity";
    object result = cmdInsert.ExecuteScalar();

    if (object == DBNull.Value)
    {
       return -1;
    }
    else
    {
       return Convert.ToInt32(result);
    }
}

OleDbConnection connection =  String.Format("Provider=Microsoft.Jet.OLEDB.4.0;Password={0};Data Source={1};Persist Security Info=True",dbinfo.Password,dbinfo.MsAccessDBFile);
connection.Open();
OleDbTransaction transaction = null;
try{
    connection.BeginTransaction();
    String commandInsert = "INSERT INTO TB_SAMPLE ([NAME]) VALUES ('MR. DUKE')";
    OleDbCommand cmd = new OleDbCommand(commandInsert , connection, transaction);
    cmd.ExecuteNonQuery();
    String commandIndentity = "SELECT @@IDENTITY";
    cmd = new OleDbCommandcommandIndentity, connection, transaction);
    Console.WriteLine("New Running No = {0}", (int)cmd.ExecuteScalar());
    connection.Commit();
}catch(Exception ex){
    connection.Rollback();
}finally{
    connection.Close();
}