WalkSpeed is not a valid member of model? What did I mess up?

Here is the local script.

local player = script.Parent.Parent.Parent.Parent.Parent
 local Player = game.Players.LocalPlayer
if game:GetService("MarketplaceService"):UserOwnsGamePassAsync(player.userId,4937288 ) then
	script.Parent.Visible = true
    script.Parent.MouseButton1Click:connect(function()
     if Player.Character.Humanoid.WalkSpeed == 16 then Player.Character.WalkSpeed = 50
        end
    end)
else
    script.Parent.Visible = false
end