Standard PO and Service PO Quantity issue

Hello All,

I am having doubt. When i try to create new Standard PO for a PR whose quantity has fully procured. i will get a error message "Enter a quantity" (Message no. 06070) . But when i do the same with service PO, quantity will be taken from PR even though services were fully procured for the PR.

Why is this so?

Please help me to clear my doubt.

Regards,

Manoj