If the angel you've selected doesn't respond, please don't take it personally. The reason could be that she's got too many connections, is busy with other matters, has dropped her phone, is sick or something else that only she knows about.
Simply select a new angel by tapping FIND MATCH or CONNECT NOW. You can leave the unanswered chat for later and can simply tap CONTINUE on all the screens until you reach the CHOOSE ANGEL since you've already created your profile.
In fact, you can select several angels and have multiple chats going until you've found someone that you feel comfortable with. Remember you're totally anonymous so there's really nothing to worry about as long as you stick to that.