What version of Filemaker?
What file are you opening? A file local to your computer or one hosted over the network? (This error message typically appears when user # 10 attempts to open a file hosted by FileMaker Pro.)
FileMakre Pro 9.0 On a Mac I am just trying to launch the program. I have a license for 3 users and have tried deleting everything on one machine so I could install program on new machine.
Filemaker Pro 9.0 had a web based activation scheme that proved so troublesome for users that Filemaker discontinued using it for subsequent versions. I believe that you can call customer service for help getting your new install of the software correctly activated.