Items - Valuation Rate / Selling rate (under Sales Invoice) problem

How can i add item which don’t have valuation rate / selling rate but i need to maintain stock?

Please proceed to close this ticket, i have solved my problem, by create item do not check the maintain stock at 1st, then go to the item to edit n checked back the maintain stock, then go to stock entry to receive stock and choose “allow zero valuation rate” .