I've been updating some of our class entries in the class forums (http://escapefromunderdark.com/forums/forumdisplay.php?f=39) so that players have a better sense of what is required to earn certain prestige classes.
It is recommended to review these posts before applying and/or to get a sense of why your app may not have been approved.
As always, please don't find a rejected app to be too discouraging. That is definitely not our intent.
Prestige classes are very prestigious and can be challenging to earn.