Amoka, I'm no expert on this stuff and am still learning but I have a few tentative suggestions about what went wrong aside from what others have correctly pointed out in previous posts.
You wrote "... I waited waited waited and waited for her for a good half-an-hour hoping to see her through the doors but there was no sign of her. I have a policy of not waiting for anybody more than 10mins so after 10mins of my waiting period elapsed, I decided to leave. I left."
Did you wait 10 minutes or half an hour. Is it good for your self-esteem to violate your own waiting policy?
You wrote "By the way, she was at home. And was sleeping when I called. "
She was at asleep!? At home! Man, that sounds like a very low interest level to me! And a major disrespect.
You wrote "Well, I'm not that busy but from what I've learned from this forum so far, one should never make the girl suspect he is free all the time and ready to go out with her whenever she wants. So I told her I will get back with her very soon. Did not mention when."
I reckon what I've picked up from thise site, and it makes good sense to me, is that you actually need to BE busy, as in having a life rather than pretending to others that you are busy. That way, if she flakes on you then its no big deal to your ego, pride etc.
Hope that helps.