How do you make something shoot at a random person touching a part?

Im trying to make something shoot at a random person touching a part, and I have no idea why my script isnt working ive debugged it and everything. This is in a normal script.

Here's the script:

potentialtarg={""}
ready=false
function onTouch(part)
	local hum=part.Parent:FindFirstChild("Humanoid")
	if hum~=nil then
	local name=part.Parent.Name
	for i=1, #potentialtarg do
		if name~=potentialtarg[i] then
	table.insert(potentialtarg,1,name)
		end
	end
end
end
script.Parent.Touched:connect(onTouch)

function onExit(part)
	local human=part.Parent:FindFirstChild("Humanoid")
	if human~=nil then
		local nombre=part.Parent.Name
		for i=1,#potentialtarg do
			if nombre==potentialtarg[i] then
				table.remove(potentialtarg,i)
			end
		end
	end
end

script.Parent.TouchEnded:connect(onExit)

function Fire()
	for i=1,#potentialtarg do
		local targ=math.random(potentialtarg[i])
		local target=targ.Torso
		local new=Instance.new("Part",game.Workspace)
		new.name="Fireball"
		new.Position = CFrame.new(46.4, 4.3, -53)
		new.Size = Vector3.new(3,3,3)
		local rock=Instance.new("RocketPropulsion",game.Workspace.Fireball) 
		rock.MaxSpeed=100
		new.RocketPropulsion.Target = target 
		ready = true	
	end
end
	


z=5
while true do
	if ready==true then
	Fire()
	wait(10)
	end
end