incorrect ATP quantity when re-acquired "Enter"

Dear colleagues,

I have a problem with ATP check in outbound delivery. When user creates delivery and enter quantity, more than we have in stock, SAP do not confirm required quantity and show error message and correct ATP quantity.  However, ifthenhe pressEnter again; SAP shows error message and incorrect ATP quantity (More than it actually is). Moreover, if user press enter several times the system confirms the requested quantity, which is not reallythere.

How can we overcome this issue?

Thanks in advance!