Try Posting an Ad on Craigslist. When I'm looking to recruit a new child I look for wanted posts on craigslist when I'm posting my Ad. Daycare providers who are serious about taking on new children should answer this ad. I know I jump on them.
It may also be the age of your child: I know I can't take anymore babies and indicate that but people keep on emailing me requesting to place children under the age I have posted. This doesn't excuse rudeness by not answering but may be part of the reason. Older cildren are easier to place than younger children (from my experience at least)

Try calling those who give numbers as well. Its easier to get a hold of people by phone. Not everyone checks their email regularily

Good luck in your search