I am guessing that your server runs fine without omnibot ? the easiest way to get it running is get your server running without it, install omnibot into its own directory, mines is omnibotv082 make sure the server still runs, then add the omnibot stuff near the bottom of your silent config, again mine is
// Omni-bots
set omnibot_enable 1 //changed from 0
set omnibot_path "/usr/local/games/enemy-territory/omnibotv082/" //changed from ""
set g_bot_maxXP 1000 //changed from -1
set g_bot_minPlayers 8 //changed from -1
set omnibot_flags 262160 //changed from 0
then it should work, do not for get you have to have a map that has waypoints as the first map or the bot will not join the server (they don't on mine) the easy way to tell if its working if there are no bots on is to do a
bot version
in the console or something like rcon unlimited and you should get
10:14:31 pm:> bot version
-------------------------
Omni-Bot : Sep 15 2013 16:27:32
Version : 0.83
Interface # : 17