There may be a possibility that your baking powder was old and stale. Always ensure that your baking powder is fresh and in a working condition. To test if your baking powder is still active, pour ¼ cup of boiling water over ½ teaspoon of baking powder. If there if foam and bubbles, your baking powder is active and good. If not, then your baking powder is not active and you need to toss it.