Need advice re toggling on-screen button

#include <GUIConstantsEx.au3>
#include <StaticConstants.au3>
#include <WindowsConstants.au3>
#include <Misc.au3>
#include <SendMessage.au3>
 
AutoItSetOption ("TrayIconDebug", 1);0-off
 
Opt("WinTitleMatchMode", 1)
 
HotKeySet("{ESC}", "Terminate") ;ESC to bail out
 
 
;Create a form 10px larger than the button I'm going to display
$Form1 = GUICreate("Test", 205, 205, 516, 25, BitOR($WS_SYSMENU,$WS_POPUP), 0)
 
;Use a blank gray image that's the same size as the above form
$Pic1 = GUICtrlCreatePic("mutebg.jpg", 0, 0, 205, 205)
 
GuiCtrlSetState(-1,$GUI_DISABLE)
 
;The initial "button" I want to show
$PicMute = GUICtrlCreatePic("Mic-Off.bmp", 0, 0, 200, 195)
$MuteState = "mic_off"
 
GUISetState(@SW_SHOW)
 
;Wait for user to click on my "button" image.
While 1
    $nMsg = GUIGetMsg()
    Switch $nMsg
        Case $GUI_EVENT_CLOSE
            Exit
 
        Case $PicMute
            Call("Mute")
    EndSwitch
WEnd
 
 
;When the user clicks on the "button this routine toggles between button states and will eventually execute some additional code if $playState="mic_on"
Func Mute()
   if $MuteState="mic_off" Then
        $MuteState="mic_on"
        GUICtrlSetImage($PicMute,"Mic-On.bmp")
        ;unmute code
    Else
        $MuteState="mic_off"
        GUICtrlSetImage($PicMute,"Mic-Off.bmp")
        ;mute code
    EndIf
 
EndFunc
 
 
Func Terminate() ;process ESC key
    Exit 0
EndFunc