This is better posted in the help/general section but i can tell you that I have only had that problem occasionally and it was always a result of the person sending the wrong file
. I sometimes accidentally sent the wrong file myself .
There are some default filenames that the game provides but I usually name my files according to whom it is being sent. So if you and I were in a game that we called "sealurk" then a file to you might be named sealurk-funk-2103. Do you and your opponent use unique file names to avoid confusion? Also are you sure that your opponent hits "Save and exit" to end his turn? Have you tried playing with anyone else?
if you want to test this you could email me at
sharris4141@yahoo.com . I would create a MP game for us and we could send it back and forth a few times to see if there is a bug somewhere. I haven't heard of this type of bug nor experienced it so the easiest answer is that your opponent keeps attaching the wrong file.