vb.net 调用 java 写的 webservice 服务传参问题

各位大神：
      在vb客户端怎么传入参数到java写的webservice的服务端？能够连接成功，传入参数就说参数不正确-----------“Client:Incorrect number of parameters supplied for SOAP request HRESULT=0x80070057”。        
      vb端代码：
       Dim soap As New MSSOAPLib30.SoapClient30
       soap.ClientProperty("ServerHTTPRequest") = True
       Call soap.mssoapinit("http://192.168.2.38:7777/ws?WSDL")
       If  Err <> 0 Then
          MsgBox "初始化SOAP失敗 " + Err.Description
       Else
          MsgBox "初始化成功"
          Dim lkk As String
          Text = soap.sayHello("hello")
          MsgBox Text
      End  if

 求大神指教！，谢谢