ExecuteWSDLAppjava.rmi.RemoteException: Service call exception; nested exception is:

Hi experts,

Im try to execute a WSDL , from my webdynpro DC , it is giving exception when executing as shown below

ExecuteWSDLAppjava.rmi.RemoteException: Service call exception; nested exception is:
com.sap.engine.services.webservices.jaxrpc.exceptions.InvalidResponseCodeException: Invalid Response Code: (401) Unauthorized. The requested URL

was :http://xxxx:port/sap/xi/engine?type=entry&version=3.0&Sender.Service=abcdefg&Interface=http%3A%2F%2Fxxxx%2Fbxxx_report%xxxxxxxx&sap-user=xi_portal&sap-password=axis1234 at  .....

It is showing the line number where we execute the wsdl file i.e

wdContext.currentXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX().modelObject().execute();

please suggest a solution for this