Getting SoapException while calling webservice from Portlet

I have a soap based webservice provider on IS server 7.1 and I want to call this webservice from a portlet. In designer I dropped this provider service from IS browser to the view and ws_client was successfully created. But when I try to run this service I am getting SoapException as below


SOAPException( Client: [ISS.0088.9166] Binder not found for soapAction = null )

electric.util.WrappedException: SOAPException( Client: [ISS.0088.9166] Binder not found for soapAction = null )
at com.webmethods.caf.wsclient.proxy.impl.WSClientDynamicProxy.getCompatibleException(WSClientDynamicProxy.java:397)
at com.webmethods.caf.wsclient.proxy.impl.WSClientDynamicProxy.invoke(WSClientDynamicProxy.java:216)
at $Proxy0.getCustomer(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

I have no idea why I am getting this error. I would really appreciate all help from portal gurus to help me resolve this issue.

Thanks & Regards,
Sandeep