This is kind of crazy, but you should all be aware of this behavior:
I was unable to set a FileMaker script schedule on the FMS13 (I've had this problem before FMS13).
Here's what happens: I go to set the schedule, fill in the proper account name and password, but when I go to the next step to choose the script, I get the message "No scripts are available for the specified account."
I tried re-installing FM Server, recovering my file, even creating new permission sets.
BUT the solution turns out to be simple: if you click the "Next" button once more, you can select the scripts. If you cancel or go back and then try again, you'll get the same error message. Just click "Next" a second time.