As I’ve stated in the past, no one in the HISTORY of CONTROLLED STUDIES has NEVER NOT lost weight while being placed on a caloric deficet.
Meaning, you gotta eat less calories than your body burns. Use something like this, http://caloriecount.about.com/cc/calories-burned.php , estimate what your maintenance calories are, take 500 from it, eat that much a day, and go from there. Adjustments can be made along the way, and cardio a few times a week will help too.