Hi Justin Paikos:
Thanks for posting.
The first thing you want to check is whether the correct extended privilege is enabled on each database. Open each database in FileMaker Pro and under the file menu select manage and security. Go to the Extended Privileges tab and double click on [fmapp] Access via FileMaker Network. Check off each privilege set which will be used to access your database. This needs to be done on all three database files.
You also need to check that each data source path is setup correctly. In your secondary databases, go under the file menu and select manage and External Data Sources. The main database needs be listed here. If you see the main database, select it and go to Edit button. In the Edit Data Source window, check the path being used for the main database. Since all three databases are hosted by FileMaker Server, you can use a relative path like file:maindatabase.fp7. Let me know if checking these settings helps with the issue.
Also check that the files have Sharing set appropriately in and that the FMS options are set for sharing.
Filemaker Pro: File: Sharing: yadaya
You should not have to 'Open' each file separately and manually. Add the Open File step for each in your main file's startup script. Use a menu button to open the other files main menu. No need to use the Open Remote at all.
You can also create an Open File file with buttons to your files and tables anywhere in the world. One tiny password protected file doe it.
I managed to get it working by setting up a VPN and running FMG through that. I think its probibly a "safer" fix.