im getting the message "keyCode is not a valid member of Enum" how do i fix this?

im really inexperienced so it would be great if someone helped and walked my through this!

local UserInputService = game:GetService("UserInputService")
local Character = script.Parent
local Humanoid = Character:WaitForChild("Humanoid")
local isRunning = false

UserInputService.InputBegan:Connect(function(key)
    if key.KeyCode == Enum.Keycode.LeftShift then
        if not isRunning then
            isRunning = true
            Humanoid.Walkspeed = 32
        else
            Humanoid.Walkspeed = 16
            isRunning = false
        end
    end
end)

(not mine)