FM 12 files won't open in my version of FM12...WHY?

I received a set of files from a coworker who is using Framemaker 12, but I am unable to open these files using my version of Framemaker 12.  We are both on Windows machines and both using FM 12. 

Although xxxx.fm appears to be a FrameMaker document, it can't be opened with this release of the product. 

There are no updates available to FM 12 that have not already been installed.

Any ideas why I can't open these files?