Connect to home L2TP VPN from outside home network

I would like to set up a L2TP vpn on my router that would allow me to connect to my home network from my macbook Pro and assign me an IP from the home network.

I have followed the thread below, but I can not get the VPN to respond when I try to connect. I just get a message saying that the server failed to respond.

I have configured it according to the thread below. Any advice would be greatly appreciated.

http://forum.mikrotik.com/t/l2tp-ipsec-vpn-access-for-mac-os-x-10-5-client/27176/1

Is your MacBook behind NAT? You might want to make sure about that, because there is an issue with such setup: http://forum.mikrotik.com/t/ipsec-and-nat-t-problem/30115/1 . I faced it when I was trying to set up IPSec/L2TP VPN on my XP laptop. You must exclude this one before you take any further actions. Also enabling ipsec and l2tp event logging on your mikrotik should give you mode idea of whats happening when you try to connect.