Why would this script when trying to run a tram system I made not work?

UIS = game:GetService("UserInputService")
local Seat =  script.Parent -- Path to seat

Seat:GetPropertyChangedSignal("Occupant"):Connect(function()
	if Seat.Occupant ~= nil then
		local Char = Seat.Occupant.Parent
		UIS.InputBegan:Connect(function(input)
			if input.KeyCode == Enum.KeyCode.W then
				while task.wait() do -- a loop
					game.Workspace.TrainKit1.Base.AssemblyLinearVelocity = script.Parent.CFrame.LookVector*-15
				end
				while task.wait() do -- a loop
					game.Workspace.TrainKit2.Base.AssemblyLinearVelocity = script.Parent.CFrame.LookVector*-15
				end
		end
		end)
	end
end)