WCF Service host in windows service

Question

I create WCF service library and i test that working fine on WCF Test client(default). when i host the WCF service in winodws service that time i got the error. I am using windows XP sp3, .Net 3.5 and Visual Studio 2008. i got error.
Error opening host : HTTP could not register URL "http://+:8731/WCFServerDLL/Service1/." Your process does not have access rights to this namespace (see "http://go.microsoft.com/fwlink/?LinkId=70353" for details).
the above link for microsoft i implement the httpcfg.
Here i run the "httpcfg.exe set urlacl /u "http://localhost:8731/WCFServerDLL/Service1/ /a"
i get the result
HttpSetServiceConfiguration completed with 0.
what is the problem i got same error. can you give me a suggation.