URGENT - Visual C++ ADD-IN Developed for OFFICE 2000/2003 is not working for VISTA

We have created an ADD-IN which gives an additional Menu (on Right Click) when a word is selected within
WORD
EXCEL &
Internet Explorer

It works for XP/2000 and Office 2000/2003 and IE 6.0/70

But when we install for VISTA and Office 2007 it does not work . I have a feeling that problem may not be for Office 2007 as its not working for Internet Explorer under VISTA

Hope to get an answer soon.

There could be any number of things going on. I suggest you go to the http://msdn2.microsoft.com/en-us/win.../aa904987.aspx
Application Compatibility web site and check out the "Cookbook" link.