Create account 400020 for someday as a cost element in controlling area ?

Dear all:

My R/3 edition is 4.70. In client 800, I created a subcontracting P/O for a semi-finished material 101-100. It has 3 components whice are raw materials. When I used MIGO_GR to make goods receipt for this subcontracting purchase order. I entered all field and saved it. But the system show me error message like this: "Create account 400020 for 2009.01.28 as a cost element in controlling area 1000".

What's happened? How can I resolve this problem?

Please help me!

Paul