Mute/Unmute hotkey, problem with notifications via Applcescript

Hello! Im currenty making a script for my macbook to mute/unmute, if I press a specific button. So far, that works. But I also want to receive a notification and when im sending a notification via applescript, it gehts shown in the notificationcenter, but it doesnt pop up on my screen. Even better than such a notification would be the hud thing, but i dont know, how I can give it the right text... (the text should be "muted" or "unmuted")
here is the code:
tell application "Finder" to activate

set inputVolume to input volume of (get volume settings)

if inputVolume = 0 then

set inputVolume to 100

display notification "unmuted" sound name "Frog.aiff"

else

set inputVolume to 0

display notification "muted" sound name "Frog.aiff"

end if

set volume input volume inputVolume

P.S. there is also no sound from the Frog.aiff