What version of Poser do you have? You should have at least Poser 4.03. It's likely that whoever's MAT file you're using has a later version than the software you have. If you have the patched P4, then you have version 4.03. If you have PPP, it's something like 4.2.01. (I forget the exact number.) P5 is 5.02 something. If I make a MAT file in P5, it will also have that 5.02 yadda number, and if you open it in P4, P4 will go, "Hey, I'm only v 4.03. Whaddya mean there's something newer?" 99 times out of 100, it will still work just fine. If it annoys you, just open up the MAT file (.cr2, whatever) in a text editing program and change the version number to read 4.03. It's up at the top, so it's easy to find. It's highly suggested to merchants that they make sure the version number in their files say 4.03 no matter what version of Poser they create their files in. Cheers!