No Item Category Assigned to account (purchase/sale)/ company code

Hi,

while posting through F-02, 40 purchase acc d/r Rs5000

50 cash a/c c/r Rs5000

it will accept and i can simulate the document also.

while saving the document the following Error occured

"There is No Item Category Assigned to account (purchase/sale)/ company code."

awaiting for the reply

Regards

Ganu