Why does it say unable to cast value to object?

Here is my script:

local region = Region3.new(Vector3.new(script.Parent.Reg1.Position), Vector3.new(script.Parent.Reg2.Position))

while true do
	wait()
	local touching = game.Workspace:FindPartsInRegion3(region, 1000)
	for i,v in pairs(touching) do
		if v.Parent:FindFirstChild('Humanoid') and v.Parent:FindFirstChild("HInfect") then
			local number = math.random(1,10)
			if number == 1 then
				v.Parent.HInfect:Destroy()
			else
				v.Parent.Humanoid:TakeDamage(v.Parent.Humanoid.Health)
			end
		end
	end
end