am calling some web service which is developed in java
I have added web reference it is doing god but when I call any function of any class in service am getting error

Code:
The request failed with HTTP status 401: Unauthorized.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Net.WebException: The request failed with HTTP status 401: Unauthorized.

Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[WebException: The request failed with HTTP status 401: Unauthorized.]
System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall) +551137
System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters) +204
com.rephero.billing.WebServicesSessionLocalService.getUserId(String in0) +79
JBillingWebReff.Page_Load(Object sender, EventArgs e) +47
System.Web.UI.Control.OnLoad(EventArgs e) +99
System.Web.UI.Control.LoadRecursive() +47
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1436

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Version Information: Microsoft .NET Framework Version:2.0.50727.1433; ASP.NET Version:2.0.50727.1433
The username and password is given correct what the problem Please help me any body