Why is GetChildren not selecting things from my list?

In my game, there is a model called OilTanks with several models in it. This script is supposed to get the children of OilTanks, select a random model, and find a UnionOperation named Tank in the randomly selected model.

repeat
	wait(1)
	c = game.Workspace.OilTanks:GetChildren()

for l = 1, #c do
	local b = math.random(1, #c[l].Name) -- chooses a random tank

for i = 1, #b do
	if (b[i]:FindFirstChild("Tank") ~= nil) then
		print("Success")
		wait(3)
		script.MaxNumber.Value = script.MaxNumber.Value - 1
		wait(5)
wait()
end
end
end
until script.MaxNumber.Value == 0

The problem is that I get an error: "attempt to get length of local 'b' (a number value)" pertaining to "for i = 1, #b do" Also, would it be better if I just named the models to be randomly selected "Model1", "Model2"?

• Workspace
  • OilTanks
    • Model
      • Tank
    • Model
      • Tank
    • Model
      • Tank

The you provided doesn't seem to do at all what you described.

You want to pick a random OilTank, and if it has an object called "Tank" in it, then 'count' it.

while script.MaxNumber.Value ~= 0 do
	local allTanks = workspace.OilTanks:GetChildren()
	local randomTank = allTanks[ math.random(#allTanks) ]
	if randomTank:FindFirstChild("Tank") then
		script.MaxNumber.Value = script.MaxNumber.Value - 1
		wait(8)
	end
end

Tab your code correctly! The above also includes some minor style corrections: workspace instead of game.Workspace; the 1 is optional in math.random; ~= nil and parens around a condition are both redundant.

Though, this doesn't make a whole lot of sense to do. You'll "repick" models all the time, and there's no reason to do this strange sort of counting, since you likely won't grab every tank (since it's random) and you'll probably repick some tanks (since it's random)