What version of Bootcamp are you using (5?, 4?, 3?)? How much RAM and which iMac are you using? I often run into such situations on older hardware or with low RAM. If you put this same runtime on a regular PC with Windows 7, does it work? Do you have FileMaker Pro on that Windows machine and will it open the same fmp12 file on it too?
Thanks, Taylor, for responding with some important questions.
I am using a 21 1/2 inch iMac from the 2011 Spring line. It has 8GB RAM. I am running Boot Camp 4.0.
The problem isn't running the runtime, it is creating it in the first place. I have FileMaker Pro 12 Advanced on the Windows iMac and it runs the .fmp12 file.
I tried making the runtime on an HP laptop running XP and it did create a working runtime. Still does not work on Windows iMac.