Why doesn't this very simple WaitForChild work? [SOLVED]

print'start'
player = game.Players.LocalPlayer
print'player'
humanoid = player.Character:WaitForChild'Humanoid'
print'human'
hp = script.Parent.Parent.Character.Humanoid.Health
print'hp'
maxhp = player.Character.Humanoid.MaxHealth
print'maxhp'
fuel = player.Character.Humanoid:WaitForChild'Fuel'
print'fuel'
maxfuel = player.Character.Humanoid.maxFuel
print'maxfuel'
game.StarterGui:SetCoreGuiEnabled(Enum.CoreGuiType.All, false)

SOLVED EDIT: used a repeat() and it worked courtesy of jackctaylor

yes, downvote me because i didnt know about something, definitely the SH spirit

Keeping it short, it prints up until the Fuel variable; If I look into my Humanoid there is infact a fuel value, so i have no idea how this could happen. Any ideas what might be causing it?