Forum Post: User Defined Scripting

I have created a JobNumber UDF and added it to AR and AP invoice data entry line detail.  Now I would like to create a User Defined Script for the actual Job Number entered during data entry to be written to the JobNumber UDF.  In AR it comes from the header and in AP it comes from the line detail.  The script that I wrote checks out, but it throws an error 88 when I try to enter an invoice.  Any help will be most appreciated! Thanks in advance.