Purchase order not created?

[Rajkamal]

First of all Thank you for you reply
No any error message i found and no any change. I found this problem only i select an specific Item Category, purchase orders are created if i select other item category.
One thing more I have not make payment for these purchase orders, Because i not find the Bank Account option in Supplier >Enter a Payment to, or Receipt from the Supplier. It may be cause of my problem. Please suggest.