This might be helpfull for you .... or not, but a known repeatable problem causes scripts, that should work as scheduled serverscripts, to fail.
If your script sequence involves more than one file and if they are not placed in the same folder on the server the script will fail.
But if this is not the case I can give you another hint: We had a server scripts not working (faling with authentication errors). We then tried the same script (the scriptelements but not the entire script) copied to a clean file ... and then it worked. Then we deleted the script from the actual file and made a new one ... and now it worked.
The file in question had never crashed, had not been recovered etc.etc. But I assume that some internal damaga must have occurred.
Import Records [No dialog; "FMfile.fp7";Add; Mac Roman]
The Data source is itself as file:FMfile.fp7
The error code 100 is file missing. How can itself be missing? If you open that script and below left, select 'Server' in the pop-up then go to the Import script, has it grayed out? It would not gray out (according to the validity of the target) in 9 (and possibly 10) but it was fixed, AFAIK, in vs. 11.
Also look at your file references then check the file reference of the table occurrence (hover at the upper left arrow of your table occurrence). If itself is missing, Carsten might be right about corruption. Might it also be communication error between the client (server script) and server?
a script running, on FileMaker server, you can not import from a FileMaker file. try to use an Excel file to import from.
If you look at this article it will give you the file types it can import.
Steve Wilmes Consulting, Inc.