Goods Receipt for sales order stock

Hi everybody,

I want to receive materials for sales order stock. what I did:

1- Created a Purchase order,

2- Account Assignment = C

3- went to MIGO

4- selected PO number

5- set movement type 101 / E

the SAP give error message that you have not planned 101 / E !!!!

I searched alot but couldn\t find the solution.