VB3 application that runs on 32-bit but not on 64-bit

Question

I have a VB3 application that works on Windows XP and win 7 32-bit version but doesn't work on win 7 64-bit version. Can anyone explain why? I know that drivers have the same behavior, but this is not my case it's just a simple application that reads from Access database. And as far as I know most 32-bit applications work on 64-bit architecture.

Answer 1

The most likely reason is that it's a 16-bit application, not a 32-bit program. This is especially the case for VB3, which supported only 16-bit programs, as "gserg" noted.