duplicate job number error message

I am trying to add a new job and keep getting an error message  'You have entered a value that has been assigned to another record.  You cannot have two records with the same value.' .   No matter what value I try to use I get the same message even though there is no job with that number existing.    I am using RDA for this client.   I am set up as a user with full accounting rights and the office admin person is set up as the sys admin user.  She has no issues adding jobs.   I don't know why it won't let me add them when I have the same accounting rights as she does.  I've tried in both single user and multi user mode and keep getting the same error each time.