WiFi101 Tutorial - UDP NTP Client. Not Working

I am trying to get the WiFi101 Tutorial - UDP NTP Client: Query a Network Time Protocol (NTP) server using UDP to work. I have a Arduino Mega with a WiFi101 Shield. The program seem to run ok and checking the outlog on my router, it looks like I am sending the UDP Packet out to the correct IP Address 129.6.15.28 and port 123. I never get a reply? I don’t know much about NTP, so I have no idea how to debug.