Hi Khuram,
This is a common warning message which comes when the valuation rule is not mapped to the product types. You can assign valuation rule for product types by following the path below:
Transaction SPRO -> Financial Supply Chain Management -> Treasury and Risk Management -> Basic Analyzer Settings -> Valuation -> Other Transactions: Assign Valuation Rule via Product type
In this customization setting, you may assign the valuation rule to a product type. The message is relevant in that case, however; it is just a warning.
You may do the above mentioned customization or just ignore the warning. This should not have any business impact.
Regards,
Nishikanta