How to check if a player has a shirt?

local shirtid = 2037398414

local players = game:GetService("Players")
local mps = game:GetService("MarketplaceService")
local shirtown = mps.PlayerOwnsAsset

players.PlayerAdded:Connect(function(player)
    local success, doesPlayerOwnAsset = pcall(shirtown, mps, player, shirtid)
    if doesPlayerOwnAsset then
        local shirt = workspace:FindFirstChild(player.Name):WaitForChild("Shirt")
        shirt.ShirtTemplate = "http://www.roblox.com/asset/?id="..shirtid
    else
        print("Player doesn't have shirt.")
    end
end)

All it does is make my shirt disappear