The other users need direct access with at least "read" permission to that directory. And a recent bug report indicates that in some cases, you may need more than just read access. CP-OrderTracker must then be mounted on their computer as a shared directory.
Here's what I know about the bug:
For More Information see: http://forums.filemaker.com/posts/52cf44da3c#174697
This is one of many acknowledged bugs that can be found in the Known Bug List thread 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