Steps to find the user id:
-Click on Game menu.
-Select Neighborhood icon.
-Click on connectivity.
Under connectivity screen you can find the user id.
both can be found in Device Settings -> Zombie Lane(Down in the bottom).
Make sure you have the latest version of the game.
Could be because of some server issues and it should work after some time. Are you facing this issue permanently?Also the zombie icon in the tab connectivity is ever disconnected.