Hi,
Yours is a special situation. The TO created based on the UD was not fully processed by the system, thats why you have only one negative quant lying in 922 - PCN area, whereas there should have been a positive quant also. This situation could have come since the system was unable to find the exact quants while processing the TO based on UD. Can you check the status of the PCN number using LU03. Check the status in the field POST CHGE STATUS is T or U?