Make sure that all your macs using the Lion OS version are updated to 11v4. This update specifically fixes this issue.
For More Information see: Filemaker Pro 11 and Lion (10.7) Gold Master
This is one of many acknowledged bugs that can be found in the Known Bug List here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: http://www.4shared.com/file/8orL8apk/FMP_Bugs.html