We have a 52-year old in our class, and 2 or 3 that are 48. I'm 40, and out of the 28 in my class, I'm right in the middle age-wise. I can't tell you why they aren't calling you, but maybe check into some of the interview consultants, they might be able to give you some third-party critiques of your resume, etc and provide you with other avenues to getting noticed.