Problem with sending custom command to a service

[zurg]

Hi!
I have a problem with sending a custom command to a windows service i wrote
before. If I use ControlService it works perfectly - the service send an
answear...
but when I use WMI there's no reaction...
Thanks in advance

The code look like this:
Option Explicit On

Module Module1

Public Sub Main()

Dim objWMIService As Object

Dim objSerwisList As Object

Dim objItem As Object

Dim objItema As Object

Dim strserwis As String

Dim iCommand As Integer

Dim returna As Integer

iCommand = 200

strserwis = "test"

objWMIService = GetObject("winmgmts:" _

& "{impersonationLevel=impersonate}!\\" + "." + "\root\cimv2")

objSerwisList = objWMIService.ExecQuery("Select * from Win32_Service where
Name = '" & strserwis & "'")

For Each objItem In objSerwisList

MsgBox(objItem.UserControlService(iCommand).ToStri ng)

'always shows 21 (Status Invalid Parameter)

Next

End Sub

End Module