Error on executing Procedure NavJobScheduler

When i try to execute this query for web service:

EXEC NavJobScheduler 'codeunit',50000,'sa','sa','localhost','http://localhost:7047/DynamicsNAV/WS/DEMO/Codeunit/NavScheduler'

I get this error message:

Msg 6522, Level 16, State 1, Procedure NavJobScheduler, Line 0
A .NET Framework error occurred during execution of user-defined routine or aggregate "NavJobScheduler":
System.Net.WebException: The remote server returned an error: (401) Unauthorized.
System.Net.WebException:
at System.Net.HttpWebRequest.GetResponse()
at StoredProcedures.NavJobScheduler(String ObjectType, Int32 ObjectID, String Login, String Password, String Domain, String WebServiceURL)
.

can someone help

Regards