Check the dates of your sales history transactions vs your GL transactions. Do you have document numbers in your GL reference/description fields to help you audit the transactions? Do you have any unposted batches?
After looking at my Transaction Listings for Periods 5 & 6, I see that there are several AR invoices from period 6 that I posted in period 5. Now I don't know if I need to try to fix it somehow or let it sort itself out over the next month end. Thoughts?