File won't compress

I have a file from FTM version 2006. This won't open in FTM 2005 or FTM 2012. In 2012, it tells me to compress the file because it's too big. I can't compress it in 2005 because it doesn't take the version of file I'm using and tells me to come back to Ancestry for a newer version of FTM (but clearly, not the 2012 version because it won't read it, it's too big). I swear I've tried everything, but nothing has worked. I just want the file to compress somehow, but I can't figure it out!