Before closing a work order, we noticed that the actual material issue $ amount was less than the estimated. When checking the print material issue report, it showed that one item had been issed to the work order with a zero dollar value. We tried to back out the transaction and resissue the parts. It shows the price acurately before clicking OK to issue materials, but when you look at the inventory transactions, it says zero.  It is also changing the last cost to zero after this. What caused this to happen? Was there a zero cost when the parts were originally issued? How do I fix this so I can close out the work order?