Make sure to use the correct chat.
If you are in a CE, use the say or yell so that people know you are in the CE and participate.
If I want to do something in Bozja I simply shout for what kind of group I want. If no one invites me I leave and try to get into one of the other 2-3 open instances.
If I don't get a group in any of them I start my own group.

People are often just to lazy to lead a own group.