Was 'ANT Farm' put on the the air in part, to fulfill a quota?
Basically, Disney feels that the need (rightly or wrongly) at least one show that has a black lead or predominately, black cast (e.g. The Famous Jett Jackson, The Proud Family, That's So Raven, and Corey in the House).
http://www.lipstickalley.com/showthread.php?t=762008