[AutoIt]Problema con Gui

#include <GDIPlus.au3>
#include <WinAPI.au3>
#include <WindowsConstants.au3>
#include <GuiConstantsEx.au3>
#include <StaticConstants.au3>
#include <WindowsConstants.au3>

Global Const $AC_SRC_ALPHA = 1
Global $hGUI, $titolo, $iSlider, $hImage, $i, $timer

main()

Func main()
   
$hGUI = GUICreate("", 250, 250, 1156, 10, -1, $WS_EX_LAYERED)


_GDIPlus_Startup()
$hImage = _GDIPlus_ImageLoadFromFile(@ScriptDir & "\riquadro.png")
SetBitMap($hGUI, $hImage, 0)
GUISetState(@SW_SHOWNORMAL)

$i=0

While $i<251
   SetBitMap($hGUI, $hImage, $i)
   Sleep(40)
   $i=$i+10
WEnd

GUIRegisterMsg($WM_NCHITTEST, "WM_NCHITTEST")

$timer=TimerInit()

While TimerDiff($timer)<3000
   sleep(50)
WEnd

$i=250

While $i>-1
   SetBitMap($hGUI, $hImage, $i)
   Sleep(40)
   $i=$i-10
WEnd


_GDIPlus_ImageDispose($hImage)
_GDIPlus_Shutdown()
GUIDelete($hGUI)

EndFunc


Func WM_NCHITTEST($hWnd, $iMsg, $iwParam, $ilParam)
   if ($hWnd = $hGUI) and ($iMsg = $WM_NCHITTEST) then Return $HTCAPTION
EndFunc


Func SetBitmap($hGUI, $hImage, $iOpacity)
   Local $hScrDC, $hMemDC, $hBitmap, $hOld, $pSize, $tSize, $pSource, $tSource, $pBlend, $tBlend
   $hScrDC  = _WinAPI_GetDC(0)
   $hMemDC  = _WinAPI_CreateCompatibleDC($hScrDC)
   $hBitmap = _GDIPlus_BitmapCreateHBITMAPFromBitmap($hImage)
   $hOld    = _WinAPI_SelectObject($hMemDC, $hBitmap)
   $tSize  = DllStructCreate($tagSIZE)
   $pSize  = DllStructGetPtr($tSize  )
   DllStructSetData($tSize, "X", _GDIPlus_ImageGetWidth ($hImage))
   DllStructSetData($tSize, "Y", _GDIPlus_ImageGetHeight($hImage))
   $tSource = DllStructCreate($tagPOINT)
   $pSource = DllStructGetPtr($tSource)
   $tBlend  = DllStructCreate($tagBLENDFUNCTION)
   $pBlend  = DllStructGetPtr($tBlend)
   DllStructSetData($tBlend, "Alpha" , $iOpacity    )
   DllStructSetData($tBlend, "Format", $AC_SRC_ALPHA)
   _WinAPI_UpdateLayeredWindow($hGUI, $hScrDC, 0, $pSize, $hMemDC, $pSource, 0, $pBlend, $ULW_ALPHA)
   _WinAPI_ReleaseDC  (0, $hScrDC)
   _WinAPI_SelectObject($hMemDC, $hOld)
   _WinAPI_DeleteObject($hBitmap)
   _WinAPI_DeleteDC    ($hMemDC)
EndFunc

GUICtrlCreateLabel()