Helen, that's a really low number of submissions. Some writers get lucky, but for most of us, it takes a lot of queries to get an agent.
You can look at whether you're targeting the right agents for your manuscript, whether your query is engaging enough and captures your manuscript accurately, and whether your sample pages are strong enough (assuming you sent sample pages with your query).
As I've revised my query over the past two years (submitting in batches after rewrites), my request rate for fulls has gone up significantly. It's a much stronger letter. Then the manuscript itself was falling short. Now I'm finishing another rewrite. Hopefully one those full requests will get an offer this time.
Nada here this week. I've been too swamped with work to finish my last bit of revisions. Frustrating. I've been checking in, though, and following what's happening, chuckling, wanting to throw something at an agent or two, and wondering like hell what happened at the gas station.
I was thinking something much worse, Carleree. Maybe they'll forget in a few months. Polly, don't you dare give up. Keep subbing, keep writing.