You actually stated it very clearly. They have to feel like they've gotten to know you...the real you. Many times people will work on their stories over and over and two things may happen -

1. It comes out canned, not personal nor reflective of YOU
2. You miss important details that the listener needs to really "see" you and the situation to gain an understanding of how you think.

All of the items you quoted below are from your perspective. But do the interviewers see the same thing? I've worked with people who many times think they have a good attitude but it doesn't come across that way at all.

Bottom line, the HR portion of the interview is very subjective. If you've had the experiences you describe I highly recommend you seek some help with how you are presenting yourself at the interview. Even if you have a friend sit down with you and put you through a mock interview (one where you don't know what questions he/she will be asking) and videotape it. You might be surprised at how you are perceived.

Lori