Humanoid not detecting speed in custom character?

Hi, I'm making a custom model and I'm trying to animate with a walk cycle. I've got everything down except for the part where you call an the event in the humanoid, speed. Here's my script:

local Humanoid = script.Parent.Humanoid local animation = script.WalkAnim local animTrack = Humanoid:LoadAnimation(animation) local player = game.Players.LocalPlayer.Character

local Humanoid = script.Parent.Humanoid
local animation = script.WalkAnim
local animTrack = Humanoid:LoadAnimation(animation)
local player = game.Players.LocalPlayer.Character

 player.Humanoid.Running:connect(function(speed)
    while wait(0.5) do
        print(speed)
    end
    if speed > 0 then
           print("Player is running")
           animTrack:Play()
       else
           print("Player has stopped")
           animTrack:Stop()
       end
end)

I'm trying to make it so that when the character walks/its speed is greater than 0, it plays the walk cycle. I tried this in play mode, but it prints "Player has stopped" but never "Player is running" when I walk, I added the print(speed) to see what was happening and it's always printing 0, no matter what move I make. Any help? Thanks in advanc