Get Slider Position for non-MS Sliders

[JPeters]

I'm trying to get and set slider positions in a program that uses "Slider20WndClass" sliders, not the "msctls_trackbar32" that I understand _GUICtrlSliderGetPos was written for. The only information I could find on getting and setting slider positions in non-AutoIt GUIs suggested using _GUICtrlSliderGetPos. Here's the code I have currently:

#include <GUIConstants.au3>
#include <Misc.au3>
#Include <GuiSlider.au3>

Opt("WinTitleMatchMode", 2);set partial match mode for window titles
WinActivate("Calibration")
$h_slider=ControlGetHandle("Calibration", "", "[CLASSNN:Slider20WndClass1]")
$SliderPos=_GUICtrlSliderGetPos($h_slider)

$GUI=GUICreate("Slider Setting", 200, 100)
GUICtrlCreateLabel("Slider = " & $SliderPos, 50, 20, 150, 30, $SS_LEFT)
$OKButton = GUICtrlCreateButton("OK", 70, 50, 60)
GUISetState(@SW_SHOW)
While 1
  $msg = GUIGetMsg()
  IF $msg = $OKButton Then
      GUIDelete($GUI)
      ExitLoop
  Endif
WEnd

The slider position comes back as -1, which I assume is an error value, for all slider positions. Can anyone suggest a way to get/set the slider position for these sliders? Thanks in advance!

[BrettF]

Maybe see what ControlGetText returns on the slider?