AHK: gdip не работает

#include gdip.ahk

F2::
file = screen.png
Screenshot(file)
return

Screenshot(outfile)
{
    pToken := Gdip_Startup()

    screen=0|0|%A_ScreenWidth%|%A_ScreenHeight%
    pBitmap := Gdip_BitmapFromScreen(screen)
    MsgBox %pBitmap%
    RET:=Gdip_SaveBitmapToFile(pBitmap, outfile, 100)
    MsgBox %RET%
    Gdip_DisposeImage(pBitmap)
    Gdip_Shutdown(pToken)
}