Condition for attribute 'productpricelevel.productid': null is not a valid value for an attribute. Use 'Null' or 'NotNull' conditions instead.

Hello,

When I am trying to add Price List on my Product form I am getting an error "Invalid Argument" and when open the Log file I am getting this error Message

Condition for attribute 'productpricelevel.productid': null is not a valid value for an attribute. Use 'Null' or 'NotNull' conditions instead. 

Please help me resolve this issue.

Its Urgent.

Thanks in Advance!!