Error:Purchasing organization POG1 not responsible for plant P1P

Hi all,

I am getting this error message as "Purchasing organization POG1 not responsible for plant P1P" while creating the PO for my newly created company code, purchasing organisation and plan. I have assigned the purchasing organisation to plant through SPRO > Enterprise Structure > Assignment > Materials Management > Assign purchasing organization to plant but still the error is coming.

Please advice.