How to make screengui enable through this short script?

while true do
for i,plr in ipairs(game.Players:GetChildren()) do
		local char=plr.Character
		print("works")
		if char~=nil then
			local t=char:FindFirstChild("Torso")
			local h=char:FindFirstChild("Humanoid")
			if t~=nil and h~=nil then
				if h.Health>0 then
				 	pos1=t.Position*Vector3.new(1,0,1)
					pos2=script.Parent.Base.Position*Vector3.new(1,0,1)
					if (pos1-pos2).magnitude<10 then
						print((pos1-pos2).magnitude)
						print("I'm close enough")
						game.StarterGui.ScreenGui.Enabled=true
						print("Screengui should be enabled")
					else
						print("I'm not close enough")
						game.StarterGui.ScreenGui.Enabled=false
						end
					end
				end
			end
	end
wait(1)
end

What this script does is checks your distance every second, if the distance is less than 10, a screen gui should enable, but it doesen't - any idea why?