What's wrong with this script?

Repost:

I want it so that when a user types another user's name into a TextBox and presses this button, the script searches for the player who's name was entered and checks to see if he's wearing a T-Shirt (I'd rather use :PlayerOwnsAsset but I can't get that to work either). Then, if the player was found owning that T-Shirt, they'd be given a tool. I've spent ages on this, I just don't know what's wrong. Please, could you help?

(I've covered up the itemID, it was an odd number).

user = script.Parent.Parent.Username
text = user.Text
dbnc = true
tool = game.Lighting.Card
clne = nil

script.Parent.MouseButton1Click:connect(function()
    if dbnc == true then
        dbnc = false
        local plr = game.Players:FindFirstChild(text) -- finds the player who's name was entered into the textBox
        if plr ~= nil then
            local shrt = plr.Character:FindFirstChild("Shirt Graphic", true)
            if shrt.Graphic == "http://www.roblox.com/item.aspx?id=NUMBER" then -- if player has shirt then
                user.BackgroundColor3 = Color3.new(0, 255, 0)
                wait(2)
                user.BackgroundColor3 = Color3.new(255, 255, 255)
                clne = tool:Clone()
                clne.Parent = plr.Backpack
            else -- if player does not have shirt
                game:GetService("MarketplaceService"):PromptProductPurchase(plr, "http://www.roblox.com/asset/?id=NUMBER")
            end
        else -- if the player who's name was entered into the textBox could not be found
            user.BackgroundColor3 = Color3.new(255, 0, 0)
            wait(2)
            user.BackgroundColor3 = Color3.new(255, 255, 255)       
        end
        dbnc = true
    end
end)