I ran into the same error with Visual Studio 2008 trying to build cppunit for 64-bit. What worked for me was changing the signature of two of the functions.
In the class cdxCDynamicDialog
afx_msg void OnTimer(UINT nIDEvent);
became
afx_msg void OnTimer(UINT_PTR nIDEvent);
so that the signature would match the CDialog::OnTimer function.
Following this through I also changed cdxCDynamicWnd
void DoOnTimer(UINT nIDEvent);
became
void DoOnTimer(UINT_PTR nIDEvent);
This doesn't cause issues in the 32-bit build because on that platform UINT is the same as UINT_PTR.