That is normal, and good.

Leaf nodes are protected from the flood of search results. The Ultrapeers that connect to you only send search requests that could match the files you are sharing, so that your machine doesn't waste time answering requests for files you don't have.

If the searches you send out are not getting many replies, however, disconnect from the network, and then reconnect. This should get you a new set of Ultrapeers, and perhaps the new Ultrapeers may be better connected to the kinds of results you are looking for.