PURCHASE PRICE CONDITION TYPE

Dear all,

We use condition type PB00 for basic purchaing price.

When we creat PO, the purchasing price come automatically as a master (inforecode)

I want to change the price manually when creating PO.

So, I changed customizing in IMG.

Material management - Purchasing - Condition - Define price determination process - Define condition type

From here , I changed setting value for "changed which can be made" as "C".

But It's not possible to put the value manually when creating PO in ME21N .

How should I do to change the price manually?

Please answer kindly....

Thanks