Any help with a Health GUI?

Can someone tell me why this Health GUI won't work? Output give's no error's.

local player = game.Players.LocalPlayer
local char = player:WaitForChild("Character")
local text = script.Parent:WaitForChild("Text")
local frame = script.Parent:WaitForChild("ColorFrame")

game:GetService("StarterGui"):SetCoreGuiEnabled(Enum.CoreGuiType.Health,false)

char.Humanoid.HealthChanged:connect(function()
    frame:TweenSize(UDim2.new(0,2*char.Humanoid.Health,1,0),"Out","Quad",0.1)
    text.Text = "Health: "..math.floor(char.Humanoid.Health).." / "..char.Humanoid.MaxHealth
end)