You simply may not be meeting all of the conditions of the fare rules with the date(s) you want to book on AA.com to get the lower fares. In your case, maybe the date you want to depart is not far enough in advance to qualify for the lower fares, but that is just a guess. My experience with AA.com is that if you meet the conditions for the lower fare that is shown on EF then that is what you will get.

As suggested above, email expertflyer with the specifics of what you are trying to book and they will help sort it out for you.