Thank you for your post.
This error message came up during our testing only with Snow Leopard (Mac OS X 10.6.x) and using a language other than English. However, this was fixed. Another customer, who encountered this same error, reinstalled FileMaker Pro 11 and the problem no longer occurred. I would also recommend updating to the most current version of FileMaker Pro 11 (11.0v2) via Knowledge Base Article #7726:
Please let me know if you continue to run into difficulty.