Hi Calgarymom, I understand your frustration! If you think it might be your daycare area, how about asking a friend to come in and give her perspective of your area. Fresh eyes can give a different perspective of your daycare.
Also, try not to let your anxiety to fill the spot show during the interviews. Trying to be too accommodating can give the sense that you are desperate. When showing your daycare, exude confidence with out being arrogant. Clients like to see you are proud of your daycare, and always pay special attention to their little one so they can see you interact with their child. That is always a lasting impression the clients take away.

Good luck filling your spot.