You cannot define a new game because your null level does not allow you to play more than 5 games at once and you are already playing (including your game invitations) 5 games.
You can solve this unpleasant situation by upgrading your membership.
(hide) If you are waiting for your turn, click on "change" next to the "refresh" on the main page, then set refresh the page to 30 seconds to get your turn to move displayed faster. (Servant) (show all tips)