Yeah, it usually happens to me after i play in a deathmatch, and then try to fight in some other mode. i think there's a bug that won't let you do that until the deathmatch is completely over and the ranking screen comes up (you have to stay in the DM room).
problem is, sometimes it takes a while, and you can miss several minutes of the next tournament. so, that's why i never play DM...
It can happen sometimes when you leave a fight befor its finished (or when your having conection problems) and go to a different room and try to fight anuther player Or when you open two fight screens by mistake.
The Urban Rivals team is made by lovers of all kind of Collectibles Cards Games and Trading Cards Games like: Magic the Gathering, Dominion, Vampire, Yu-Gi-Oh!, Pokemon, Wakfu TCG, Assassin Creed Recollection, Shadow Era, Kard Kombat and Might & Magic Duel of Champions.