Why is it so hard to get a job interview?

I've been submitting to jobs through the career site for Discovery Communications since--get this--May 2005!~ Even though I'm very well qualified for many of the positions, I have never been called in for a single interview. (Although I have received two phone calls over the years by members of the Human Resources department at the company to confirm certain qualification information.)

Is a person really looking at my qualifications? Is their automated system looking for something that my resume just doesn't have? I have modified my resume a few times, as well as my job seeker settings (such as my required salary) just to make sure the problem wasn't on my end.
To date, I've not found any problems with my resume, but I've still not received a single call requesting a job interview.

I'll keep trying, though. Discovery is a media company within a reasonable driving distance from my home, and there just aren't that many locally-based companies where I can work in the entertainment media field.