Game pass script isn't working, can someone show me the correct way to do it and explain?

local passId = 379480149
function isAuthenticated(player)
    return game:GetService("GamePassService"):PlayerHasPass(player, passId)
end
script.Parent.VehicleSeat.ChildAdded:connect(function(obj)
    if game.Players:FindFirstChild(obj.Part1.Name) then
        plr = game.Players:FindFirstChild(obj.Part1.Name)
    end
    if plr and not isAuthenticated(plr) then
        plr.Character.Humanoid.Jump = true
        print(plr.Name.." is not authorized to use this vehicle")
    end
end)

I put this script into the seat of the vehicle which is named Drive, and the id is correct and I'm sure of that. Though when i try to test it with someone who doesn't have the pass, they can still drive it and they don't jump out. I tried multiple ways to do it and still. I tried to find the problem, but couldn't find it. Although "plr" on line 7 is underlined in blue. Can anyone help?