Duke Nukem Atomic question

I recently bought Duke Nukem Atomic over the net. I downloaded it. Very quick and works great. I have three expansion games that worked great with the original Duke Nukem Atomic I used to have. They don't work with this newly purchased game however. How do I know what version I have bought? It makes a difference. Or could it be a matter of what I bought over the net being "upgraded" in some way to work with modern PCs so that now they are no longer compatible? The expansions can't seem to find the source game. The expansions are Duke!zone, Duke it out in DC, and Duke Nuclear Winter. Hey, if I can't have Duke Nukem Forever then I need the old Duke. Thanks in advance.