Hi!

Two suggestions:
1. set coverage to ... on the Specified Program code
2. Sideload your code ;) (with a little adjustment of your existing code)
Ok Explanation: take your xxx.prg file to the customers System.
In your Applicatoin, at the correct point of code, do an compile xxx.prg command
then execute the xxx.prg
If an error raises you will get the right Line of Code