Hi RPope
I am in the US and don't use PayDirt, but I have seen this message with the payroll software we use here.
What you need to do is open up the file PRAJBTCH.xxx (where xxx is your data extension) using Wordpad, then scroll down to line 634 and take a look at that entry. If necessary, fix the job number or delete the line. Or create the job in JobCost and try again. The file is in your data directory, and it is a text file.
Steve