Dear Purna
Please go through the entire settlement process
Settlement can be done from lower level WBS elements and NWA to upper level WBS elements and there by to the profitability segment or To WBS elements or to the GL account or to an asset,as the case may be.
Maintain the settlement rule in every activity either by configuration or manually depending upon the requirements.
For Settlement please go through the SAP Help and also there are many links and questions available over to the SCN