From what you have told me you only have one radio button that has a CButton that is associated with it. Try this instead of calling m_radioGrp.CheckRadioButton(...) call the CDialog version CheckRadioButton(...). That call is from the CWnd class, so even though you can call it with your CButton class, it doesn't make sense. You can either call the CheckRadioButton(...) or map 3 CButton classes (each of your radio buttons) and call the member functions such as SetCheck.

Wayne