CRM4.0 ISA Enhance debug

Hello,everyone

I want to Enhance the CRM4.0 ISA interface With NWDS as the document:SAP_ISA4DevExtG10. I interrupt the standard process of the B2C and insert my new action. When I insert my new action in the B2C application my process is stopped. My java action is correct in NWDS. But when I check the B2C application log in the server, it displayed that my B2C application is stopped at the new action. I want to debug my B2C application with NWDS, I refer to the SAP help to debug ,But I failed!

Anyone who can help me ?

Thank you