Java Web Service call from C# windows application returns "Object reference not set to an instance of an object"

Dear Experts,

I'm using web service exposed from a website to submit my client transaction and get the response back.i'm passing correct parameters to web service in the correct formats the same web service call with the exact same parameter is working when I'm using testing tool SOAPUI but when I'm running through my c# code getting the exception "Object reference not set to an instance of an object".

Below is the signature of web service function :

int WebSvcFunction(string login,string pwd,string xmlClaimInput,out string xmlDRGDetails,out byte[] auditFileContent,out byte[] reportFileContent,out string errorMessage);

Any help in this regards is highly appreciated.Thanks in advance.

Below is my sample code for Testing :

private void btnTestService_Click(object sender, EventArgs e)
  {
         try
         {
               string xmlDRGDetails = (string)null;
               byte[] auditFileContent = (byte[])null;
               byte[] reportFileContent = (byte[])null;
               string errorMessage = (string)null;

               int m = objWebservicesSoapClient.WebSvcFunction(gstrLoginId, gstrpwd, rTxtDrgTab.Text.ToString(), out xmlDRGDetails,
                                                       out auditFileContent , out reportFileContent, out errorMessage);

               MessageBox.Show(string.Format("Success {0}", m));
          }
          catch (Exception ex)
          {
               MessageBox.Show(string.Format("Source: {0}\nDescription:{1}\nTarget Site:{2}\nCall Stack:{3}", (object)ex.Source, (object)ex.Message, (object)ex.TargetSite, (object)ex.StackTrace), "Convert DRG", MessageBoxButtons.OK, MessageBoxIcon.Error);
          }

         }