I believe that every NPC sorority's membership selection process is secret and ritual. The only people who know the reasons you were cut are the people that were in that room, and they are vowed to secrecy.
Asking what went wrong isn't going to get you an answer. It's also kinda tacky, IMO.
With something like grades, it's pretty obvious. If XYZ sorority requires a 2.5 and you have a 2.0, it's clear.
If someone gives you some reason you were cut, they're probably just trying to think of something because they're put on the spot. Sometimes they may be saying something nice, even though the reason you may have been cut may have been not-so-nice.
BTW- this is all a collective "you" as in "you, sally PNM"
Bottom line is, don't ask. They're not going to tell. If they do, it's probably not the truth.
ETA: what are they supposed to say? we cut you because your super long nose hairs scared us and you wore marilyn manson t-shirts and carried around a dead cat for all of rush?