Replying to Party

My neighbor, who is my age, goes to my school, that i have known for 11 years is having a party tomorrow night. Nothing huge but something more then a get together. Were seniors and since he doesn't want it to get out of hand he has a list of people that are going, and im not there? I don't get it either, we've gone to parties together, we hang out, or parents work together ... and its not that im just automatically there that im not on the list. So i don't get it.. i tried the "joking" method of bringing it up in conversation and he shot it down immediately. I'm not a begger so i'm not going to ask to go, so i don't know what to do. any ideas on any of this