I've been having a lot of trouble getting agents to bother to look at my manuscript, because I'm a first time author, no credentials (besides a BA in Creative Writing) and I'm writing something that blurs a few genres and isn't the norm for genre fiction.
I second Michael's advice. It's a myth (put about by vanity presses and disgruntled writers) that agents and publishers aren't interested in first-time authors. I have one short story credit, in such an obscure e-anthology that I didn't even bother mentioning it in my query. Hasn't stopped me getting requests for the full ms of my alternate history fantasy espionage thriller (since we're talking genre-blurring...)
If you aren't getting requests for partials, it means one of two things:
1. You haven't tried enough agents yet.
2. Your query isn't quite there yet.
Have you tried posting your query in SYW (Share Your Work) here on AW?