Providing you have good, tested MDMA you should.
My guess would be not 'letting go' so to say. When i'm rolling I could hold back and not speak to people but I just allow the love and good vibes to take control which leads me to chatting to people. Just relax, let the MDMA take control and see who it warms you to. I normally find myself warming to certain people more than others, normally the other loved-up ravers, which leads me to my second guess. I find you can always tell who's on your 'level' and the urge to speak to them freely takes control. On the other hand, the non-rollers don't normally attract me. I go out raving with one very close mate who's always sober and I find I barely speak to him/spend time with him once i'm up, the connection just isn't there. Once I start coming down I rave with him more and don't feel so comfortable with strangers. Two people on MDMA = instant friends.
Maybe apply some of what I experience to the setting you roll in: is everyone else rolling? Do you just let go of social fears? Are you extremely introverted sober?
Just some thoughts. Remember, drugs affect us all differently maybe you just don't get it which is a shame cause its the best part in my opinion!