To see the text associated with an OS message just do
In your case it seems that one of those fields have invalid packed data in it.
When you get the error, arrow up to it and hit F1. This will give you the error description. Then hit F10 to see any previous errors.
I can’t remember if it is the first or second screen that gives you the line number of your program where the error occurs.
To see the line number and program name it’s necessary to hit F9 after F1.