CRM billing for service scenario - No billing Document Created

Hi,

I am trying to Configure CRM billing for service scenario. After creating the Service Order and creating a Confirmation i am getting the documents in release for billing. But when i Release the document for Billing using "Release for billing " under webgui-> service operations -> release for billing it is not generationg the billing documents.

would apprecaite if write me back the relevant procedure or settings .

Regards,