I've been reading through help center about my standardlines problem. I appear to be getting my credit and debit amount from the wrong line in standardlines. Some lines are obviously credit or debit lines, but sometimes there are lines with 0 on both. Can anyone point me to documentation on the structure of GL Lines and how they are populated?

Have you looked at this https://system.na3.netsuite.com/app/help/helpcenter.nl?fid=chapter_4072802996.html