Question about patching

Alright, I have a question about patching. Now, normally, when I patched my game, I'd just make a patch by uploading all of the maps and the database into one rar file and go from there (which has worked so far). Now, I released a new patch just recently, and it seems that people can't use their old save file anymore. What could be cause of this? Could it be due to me adding a few new areas in the game even though I had them in the new patch? Could it be that I tinkered with the database that I also added with the new patch?? I'm at a loss at what could be the issue here x_x

I think if you edit the database, the old save files won't work.

I also think, as I found out, if you don't include the new tilesets and stuff WITH the patches, then it won't work either....lol. I feel silly now x_x