Error regarding version visual studio or function declaration

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Visual-Studio

MFC

VisualC++

Hi!
I am going to convert visual studio 2006 project to visual studio 2008 but there is some error occured for button click event
In Header file function declared as
afx_msg int OnOk();

In .cpp file message map it declared as
ON_BN_CLICKED(IDC_OK, OnOk)//ON_BN_CLICKED(IDC_OK(Control_Name), OnOk(Event_Name))

& at last it defined as

int communication::OnOk()
{
    // TODO: Add your control notification handler code here
    UpdateData(TRUE);
   {
           //Some code
   }
    return 0;
}

Error shows that:-

error C2440: 'static_cast' : cannot convert from 'int (__thiscall communication::* )(void)' to 'AFX_PMSG'

What is solution for that?