VBscript and impersonation

I've tried to run a VBscript with elevated privileges, but with no success.
My code works fine, except if I try to run it using impersonation.

Have anyone made it work ? Will you try it on your installation to see if it
works? Shouldn't take more than a few minutes.

I have used the "Impersonation" setting in web.config.
I have tried Process.Start and specified username/password in

When supplying username/password to Process.Start it calls an unmanaged API,
LogonUser, so I also tried calling that directly.

But vbscript simply won't start.
It gives me this error:
Microsoft Windows scripting version 5.6 (etc... the banner-info) followed by
"Windows Script Host"...
"Can't find script engine 'VBScript' for 'C:\test.vbs'."

or "application failed to initialize properly (0x0000142)"

Googling for these suggested installing the latest version of vbscript, or
re-installing, or messing with registry-keys but nothing helped.

This is the code for a webform with a label and a button:
Protected Sub knpCommit_Click(ByVal sender As Object, ByVal e As
System.EventArgs) Handles knpCommit.Click
Dim myProcess As New Process
Dim output As String

With myProcess.StartInfo
.FileName = "c:\windows\system32\cscript.exe"
.Arguments = "c:\TestScript.vbs"
.UseShellExecute = False
.RedirectStandardOutput = True
End With

Me.Label1.Text = "efter start"
output = myProcess.StandardOutput.ReadToEnd()
Me.Label1.Text = output


End Sub

With this in web.comfig it fails:
<identity impersonate="true" userName="myDomain\myUserName"
password="MyPassWord" />

This is the script in c:\TestScript.vbs:
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objFile = objFSO.OpenTextFile("C:\ScriptLog.txt", 2)

Set WshNetwork = WScript.CreateObject("WScript.Network")
objFile.WriteLine WshNetwork.UserName
WScript.Echo "Testscript 1: Username: " & WshNetwork.UserName