Automatic PO creation from CRM Service Order

Hello All,

We have a business scenario of creating a purchase order for a part included in the service order.

Once the service order created and released , PO should be created for the part with the item category related to PO creation.

I have maintained all the configuration settings for the logistic integration b/w CRM <--> ECC.

Now while releasing the service order to ECC , Creation of PO is ending with the error message "No Source of supply found for material XXXX".

We have assigned vendor in the service order and also maintained the source list for the material in ECC.

Is there any other configuration setting which I missed?.

Please suggest.

Thanks

Syam