function won't work inside MFC dialog class

I had to put my gotSensor outside of my class to make it work. If I put
it in my dialog header file I get the following error:

error C2276: '&' : illegal operation on bound member function expression

How do I make this work inside the class or how do I access a control on
the dialog form from outside the class. It works fine in a Win32
console application, but I need to convert it to a MFC program.

   Z.K.

//////////////////////////////////////////////////////////////////////////

//outside of class
int __stdcall gotSensor(CPhidgetInterfaceKitHandle phid, void *meh, int
ind, int val);

void CTestWin32PhidgetDlg::OnBtnSensor()
{
    // TODO: Add your control notification handler code here

    int something;

    CPhidgetInterfaceKitHandle ifkit;

    CPhidgetInterfaceKit_open(&ifkit,0,-1);
    CPhidgetInterfaceKit_set_OnSensorChange_Handler(ifkit,&gotSensor,
&something);

    while(1)
    {
        CPhidgetInterfaceKit_read(ifkit);
    }

}

//outside of class
int __stdcall gotSensor(CPhidgetInterfaceKitHandle phid, void *meh, int
ind, int val)
{
    CString temp;
    temp = "hello";

    //AfxMessageBox("hello");

    return 0;
}