Why wont screen GUI appear when enabled in game?

So, I have this screen GUI. It doesn't appear when enabled in game, unless it starts out enabled. Pls help.

permission = {"Greatnate09"}

function checkOkToLetIn(name)

for i = 1,#permission do

if (string.upper(name) == string.upper(permission[i])) then return true end

end

return false

end

local Door = script.Parent

function onTouched(hit)

local human = hit.Parent:findFirstChild("Humanoid")

if (human ~= nil ) then

if (checkOkToLetIn(human.Parent.Name)) then

game.StarterGui.ScreenGui.Enabled = true

game.ServerScriptService.Script.Disabled = true

game.Workspace.Music.Sound1:Stop()

game.Workspace.Music.Sound2:Stop()

game.Workspace.Music.Sound3:Stop()

game.Workspace.Music.Sound4:Stop()

game.Workspace.Sound:Play()

game.Workspace.MusicOn.Script.Disabled = true

game.Workspace.MusicOff.Script.Disabled = true

wait(300)

game.StarterGui.ScreenGui.Enabled = false

game.Workspace.Sound:Stop()

game.Workspace.MusicOn.Script.Disabled = false

game.Workspace.MusicOff.Script.Disabled = false

end

end

end

script.Parent.Touched:connect(onTouched)