I can't enable sparkles and smoke through my code?

Here is my code:

 while true do
 wait(math.random(5,30))
 local num = (math.random(1,3))
if num == 1 then
script.Parent.Sparkles.Enabled = True
wait(5)
script.Parent.Sparkles.Enabled = False
elseif num == 2 then
script.Parent.Fire.Enabled = True
wait(5)
script.Parent.Fire.Enabled = False
elseif num == 3 then
script.Parent.Smoke.Enabled = True
wait(5)
script.Parent.Smoke.Enabled = False
end
end

For some reason none of the effects happen, they are all in the block and disabled so I can't work out why, help is appreciated.

Thanks CrystalCoder