Trying to get ALL Greek Alums together

[winneythepooh7]

So with the support of my organization, I've been planning some get-togethers to attract alums from all GLO's in NYC. I've planned about 3 events so far and no one from the other GLO's have come. I know there is also another group like this in NYC and i've emailed THEM and no one has gotten back to me from their group. Anyone have any advice on how to get people (both males and females) from other GLO's to come out for happy hours and networking events? I've also created a listserv in yahoogroups for this and send out evites. People say they're coming but then never show up.