Purchase Posting Error due to Item Charge Qty Assig

In the NAV 2009 classic version, a user gets the following message when they try to post a purchase order that has an item charge on it: “Quantity Invoiced must not be greater than Qty Assig.” The purchase line where the error is occurring has an amount of 7267, a quantity of 1, “Quantity Received” = 1, “Quantity Invoiced” = 1, “Qty to Assign” = 1, and “Qty Assig” = 0. In other words it is fully received and invoiced but the item charge is not assigned. When I find the purchase invoice for the item charge it shows the full 7267 was invoiced. When I navigate to the value entries they show an amount of 1,221 for the item charge applied to the $62,000 cost for the item. There have been three different purchase invoices created (posted) for this purchase order. The first 2 did not include this item charge. The 3rd one did. In fact the item charge was not added to the purchase order until after the first 2 purchase invoices were created.
When I debug the posting error, it takes me to UpdateItemChargeAssgnt function in the Purchase Line (39) table. I’m not sure how to fix this. It seems to me that when it was invoiced it should have assigned the entire 7267 to items and changed the “Qty Assig” to 1. Ideas to fix this?