I'm kind of new using YAHOO!, but I noticed one team drafted immediately after I set my rankings and clicked on 'ready'.
Another team I set up, and waited for a day and a half. I got frustrated, so I bailed out of that league and joined another public league. 15 minutes later I had a team drafted. My guess is your league is not filled. If you are impatient like me, try switching leagues.
* Steroid induced record