There are generally 3 causes of this.
1) The most likely cause is that you have gone "missing", meaning that you have not attended the prescribed
number of raids (see The Rules (http://eq.frayedknot.us/boards/index.php/topic,19177.0.html) for details)
2) you have not attended any raids
3) the DKP system only displays 5 players with the most DKP on the Leader Board so if you have fewer DKP than
those 5 you will find your name in the list below (Overview)