[maconmagnolia]

Membership selection information is private, but I will tell you this from my personal experience at a university in the Midwest.

Think of it this way. There are many girls going through rush. A sorority has X amount of girls they can invite back. It would be hard to choose to invite back someone they've never met (I'm assuming from what you said that you have to miss a day's worth of rush, meaning that you would miss an entire round of parties) over someone they have met and liked.