Goods Receipt unchecking causing error

Hi Gurus,

I need your help.

The scenario is

"I am trying to uncheck "Goods Receipt" flag in the Delivery Tab of PO line item. The material is NLAG one . While saving the PO, I am getting the error message "GR mandatory for PO item 00010 . No entry in GR Check Table". What config change I have to do?

Thanks,

Kumar