animation does not want to play?

I am making a custom character and the function is not firing cuz i am not getting a stuff in output

local player = script.Parent
local humanoid = player.Humanoid
local walk = script:WaitForChild("walk")
local walk_anim = humanoid.Animator:LoadAnimation(script.walk)
local walking_value = script.walking.Value

function moving()
    print("stuff")
    if not walk_anim.IsPlaying then
        walking_value = true
        walk_anim:Play()
    end
end

humanoid.Running:Connect(moving)