My health bar script works in studio testing, but not in the actual game?

I'm trying to make a game and I made a health bar. I've maid health bars before and normally this isn't a problem. I tested it in studio and it worked just like intended, but when I tested it in the actual game on roblox, it didn't work. Script:

local healthgui = script.Parent
local frame = healthgui:WaitForChild("Frame")
local number = healthgui:WaitForChild("Number")
local player = game.Players.LocalPlayer
local char = player.Character
local healthstat = player:WaitForChild("Health")
local maxstat = player:WaitForChild("MaxHealth")
local words = healthgui:WaitForChild("Health")

local green = Color3.new(0,255,0)
local red = Color3.new(255,0,0)
local yellow = Color3.new(255,255,0)

char.Humanoid.Changed:connect(function()
	local health = char:WaitForChild("Humanoid").Health
	local maxhealth = char:WaitForChild("Humanoid").MaxHealth
	local redzone = maxhealth*0.25
	local yellowzone = maxhealth*0.5
	if health <= redzone then
		frame.BackgroundColor3 = red
		number.TextStrokeColor3 = red
		words.TextStrokeColor3 = red
	elseif health <= yellowzone then
		frame.BackgroundColor3 = yellow
		number.TextStrokeColor3 = yellow
		words.TextStrokeColor3 = yellow
	else
		frame.BackgroundColor3 = green
		number.TextStrokeColor3 = green
		words.TextStrokeColor3 = green
	end
	frame:TweenSize(UDim2.new(healthstat.Value/maxstat.Value*0.93,0,0,24),"Out","Quart",1)
	number.Text = healthstat.Value.."/"..maxstat.Value
end)

while wait() do
	local level = player:WaitForChild("leaderstats"):WaitForChild("Level")
	if player.Name == "Blue_Deku19" then
		char:WaitForChild("Humanoid").MaxHealth = (level.Value * 5 + 95)*5
		healthstat.Value = char.Humanoid.Health/5
		maxstat.Value = char.Humanoid.MaxHealth/5
	else
		char:WaitForChild("Humanoid").MaxHealth = level.Value * 5 + 95
		healthstat.Value = char.Humanoid.Health
		maxstat.Value = char.Humanoid.MaxHealth
	end
end

I tested which part it fails at by making it make a part wherever your current player is and I moved that around, it didn't even make the variables in the first part. This is a local script in StarterGui, does anyone know what's wrong with it? Sorry if it's long e.e. Also, it showed no problems whatsoever in the output when I was testing it in studio.

It seems that it can possibly be one or more of your waitforchilds, check for spelling errors