Attempt to index a nil Value?

It prints Attempt To index a nil Value.

The ClassValue is an IntValue.

script.Parent.Parent.TicketChecker.Touched:Connect(function(part)
    if part.Parent.Parent:FindFirstChild("Humanoid") then
        coolDown1 = true
        local plr = game.Players:GetPlayerFromCharacter(part.Parent.Parent)
        if part:FindFirstChild("ClassValue").Value == 5 then
            plr.Character.Torso.CFrame = CFrame.new(plr.Character.Torso.Position, script.Parent.Parent.GateTP.Position)
            print("a")
        elseif part.Parent:FindFirstChild("ClassValue").Value == 4 and boardingClass <= 4 and boardingClass > 0 then
            plr.Character.Torso.CFrame = CFrame.new(plr.Character.Torso.Position, script.Parent.Parent.GateTP.Position)

        elseif part.Parent:FindFirstChild("ClassValue").Value == 3 and boardingClass <= 3 and boardingClass > 0 then
            plr.Character.Torso.CFrame = CFrame.new(plr.Character.Torso.Position, script.Parent.Parent.GateTP.Position)

        elseif part.Parent:FindFirstChild("ClassValue").Value == 2 and boardingClass <= 2 and boardingClass > 0 then
            plr.Character.Torso.CFrame = CFrame.new(plr.Character.Torso.Position, script.Parent.Parent.GateTP.Position)

        elseif part.Parent:FindFirstChild("ClassValue").Value == 1 and boardingClass == 1 then
            plr.Character.Torso.CFrame = CFrame.new(plr.Character.Torso.Position, script.Parent.Parent.GateTP.Position)
        else print("AAA")
        end
        wait(1)
        coolDown1 = false
    end
end)