Overhead camera disables character movement?

I am working on making an overhead camera for my game.

I tried this a while ago and had no issues, but however just today i tried it and i cant seem to be able to "control" my player's character. Pressing "Arrow Keys" or "WASD" do nothing.

The script itself was pretty easy, but i am puzzled on this part. I tried zooming the camera in, and out, and it still wont let my character move. The only way to actually make it work is if i change the X and Z coordinates as well when editing the camera.

Script (you can see how i only edited the Y coordinates):

local runService = game:GetService('RunService')
local function onRenderStep()
end
local offset = Vector3.new(0,40,0)
local player = game.Players.LocalPlayer
local camera = game.Workspace.CurrentCamera
local runService = game:GetService('RunService')
local function onRenderStep()
    local playerPosition = player.Character.Head.Position
    local cameraPosition = playerPosition + offset
    camera.CoordinateFrame = CFrame.new(cameraPosition, playerPosition)
end
runService:BindToRenderStep( 'Camera', Enum.RenderPriority.Camera.Value, onRenderStep)

If you know why this is then please help :P

Thanks!