Warning message, if Quantity=0, when creating a sales order with VA01orVA02

Hi Experts,

Currently, if the user do not enters any value in QUANTITY field, while creating a sales order(or even VA02 too) ..........we are getting a Warning message(VU001).

So, I need to change it to hard error message type, am changing the message type, but, its not reflecting, and still its throwing a warning message(VU001)!!

Let me know that, What is the correct user exit to incorporate my changes?

From where this message generating? am keeping a watch point with this message (VU001), but, its not stopping!!

System is ECC 6.0

repliaes appreciated

thanq

Edited by: SAP ABAPer on Dec 22, 2008 4:38 PM