QObject::connect exception fire

[names]

Hello, Qt guru
I try to implement QComboBox derived class and process signal currentIndexChanged(int)

class ComboBox_impl : public QComboBox
{
    Q_OBJECT
    public:
 
    ComboBox_impl()
    {
        connect(this, SIGNAL(currentIndexChanged(int)), SLOT(doProcessIndexChanged(int)));
    }
 
    virtual ~ComboBox_impl()
    {
    }
 
public Q_SLOTS:
    void doProcessIndexChanged(int)
    {
    }
};

class ComboBox_impl : public QComboBox
{
    Q_OBJECT
    public:
	
    ComboBox_impl()
    {
        connect(this, SIGNAL(currentIndexChanged(int)), SLOT(doProcessIndexChanged(int)));
    }
		
    virtual ~ComboBox_impl()
    {
    }

public Q_SLOTS:
    void doProcessIndexChanged(int)
    {
    }
};

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This works excellent on Mac, but on Windows exception "Access denied" occured on line

connect(this, SIGNAL(currentIndexChanged(int)), SLOT(doProcessIndexChanged(int)));

connect(this, SIGNAL(currentIndexChanged(int)), SLOT(doProcessIndexChanged(int)));

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I use Xcode on Mac and VS 2008 on Windows.

Qt version on Windows is 4.6.2

Waiting for your help,
N.