Hi,
Check the billing relevance in your Item category.
The below SAP help document may help you,
http://help.sap.com/saphelp_erp60_sp/helpdata/en/dd/5602e2545a11d1a7020000e829fd11/content.htm
also check below one, before running the report in PRD check in QAS.
http://help.sap.com/saphelp_47x200/helpdata/en/70/a7853478616434e10000009b38f83b/frameset.htm
Regards, Sai Krishna.