DataStore not saving data?

I'm trying to make a skin system that saves the values of your skins. When testing, however, my script didn't work, and I kept getting the error print. Here is my script:

local DSS = game:GetService("DataStoreService")
local SkinDataStore = DSS:GetDataStore("SkinStore")

game.Players.PlayerAdded:Connect(function(player)
    wait(1)
    local Skins = Instance.new("Folder")
    Skins.Name = "Skins"
    Skins.Parent = player

    local RoyaleMtar = Instance.new("StringValue")
    RoyaleMtar.Name = "RoyaleMtar"
    RoyaleMtar.Parent = Skins
    local DesertPGH = Instance.new("StringValue")
    DesertPGH.Name = "DesertPGH"
    DesertPGH.Parent = Skins

    local Id = "Player_"..player.UserId
    local SkinData
    local success, errormessage = pcall(function()
        SkinData = SkinDataStore:SetAsync(Id)
    end)
    if success then
        RoyaleMtar.Value = SkinData
        DesertPGH.Value = SkinData
        print("hi" )
    else
        print("error")
        warn(errormessage)
    end
end)
game.Players.PlayerRemoving:Connect(function(player)
    local Id = "Player_"..player.UserId
    local data = player.Skins.RoyaleMtar.Value
    local data1 = player.Skins.DesertPGH.Value

    local success, errormessage = pcall(function()
        SkinDataStore:SetAsync(Id, data, data1)
    end)
    if success then
        print("Skins Saved")
    else
        print("Skins failed to save")
        warn(errormessage)
    end
end)