To Direct Connect requires having open upld & downld slots & bandwidth for both parties. Also neither party being firewalled. And apparently having Chat enabled can help. See tips here:
How to Direct Connect, Browse & Chat (so tell your friends to read these points. And to do the Bug test:
Bug Report instructions & sample image And if this is True then they're not firewalled.)
I did a Direct Connect to you from my mac yesterday without problems.