THIS HAS TRIPPED ME UP BEFORE, TOO. Setting up a dropbox link with FileMaker Server can be frustrating:
In the FileMaker Server Admin Console,
1) Click on Schedules
2) Add a new schedule by clicking the small calendar icon
3) Select your databases to back up, then click ‘Next’.
4) The second screen you will see is where you set the path to where you want the databases saved. In this case, I am aiming for a folder called ‘FileMaker-Database-Backup’ inside of Dropbox.
5) Enter the Backup Folder Path
6) Click Validate
7) Check Status — It should read ‘Valid Path’
Instead, my Status read “Not a Valid Path”.
It comes down to permissions properly on the target folder. And this has happened to me on both Mac and Windows servers. Read the whole thing.