akward

Over the past few weeks I have been trying to branch out and hang out with new people. I found a couple people that I really enjoyed hanging out with, but for some strange reason it seems like they have fallen off the planet. Two weeks went by and I heard nothing from them. On my birthday they suddenly drop by and wish me a happy birthday. I was very happy that they did this, but the very next day they went straight back to avoidance mode. What should I do?