400 job openings but you can't get an interview?

I feel like I'm banging my head against a wall here

I'm a new grad RN (already sat for NCLEX & passed) and I've been trying to get an interview with two large hospitals in my area for weeks now. I've sent resumes, I've phoned, I even went to a health career fair and spoke with the HR person. She says she's been sending my resumes to the nurse managers but I've yet to receive a call from any of them. They have over 400 jobs posted on their website.

I have other interviews set up with smaller hospitals and rehab centers but I'd love to interview at the big hospitals as well.

Any pearls of wisdom from you seasoned nurses?