plugin related - animation not playing for some reason?

so im trying to make this plugin for my friend that loops through animations within a folder and then loads them into a rig's humanoid and then plays them, but this doesn't seem to work and i literally have no idea why

--//animation plugin for alimr

local toolbar = plugin:CreateToolbar("AirLive1")

local createAnimationFolder = toolbar:CreateButton("create animation folder","creates an animation folder","")
local previewAnimation = toolbar:CreateButton("preview animation","previews the animation","")


local function createAnimFolder()

    local animFolder = Instance.new("Folder",workspace)
    animFolder.Name = "Animation Folder"

    for i = 1,3,1 do
        local animString = Instance.new("Animation",animFolder)
        animString.Name = "Animation "..i
    end
end

local function previewAnimationFunc()
    local selection = game.Selection:Get()

        if selection[1].Name == "Animation Folder" and selection[2].Name == "Rig" then
            print("Yes v2")
            local rig = selection[2]
            local humanoid = rig:FindFirstChild("Humanoid")

            for i,a in pairs(selection[1]:GetChildren()) do

                print(a.Name)
                local track = humanoid:LoadAnimation(a)
                track:Play()

        end

    end

end

createAnimationFolder.Click:Connect(function()
    createAnimFolder()
end)

previewAnimation.Click:Connect(function()
    previewAnimationFunc()
end)