"if plr:FindFirstChild("String") ~= nil then" not working?

So, what I'm trying to is when you own a gamepass, you are checked if you have a folder in the Player and if there is a certain BoolValue, but if they are nil it adds them in.

game.Players.PlayerAdded:connect(function(plr)
    if isAuthenticated(plr) or plr.Name == "Player" or plr.Name =="Player1" then
        table.insert(BetaPlayers, plr.UserId)
        print(plr.Name..", "..plr.UserId)
        if plr:FindFirstChild("GPs") ~= nil then
            local ldrbord = Instance.new("Folder",plr)
            ldrbord.Name = "GPs"
        end
        if plr:FindFirstChild("isBetaPlayer") ~= nil then
            local btaplr = Instance.new("BoolValue",GPs)
            btaplr.Name = "isBetaPlayer"
            btaplr.Value = true
        end
    end
end)