Is your baking powder still okay? Test by putting one teaspoon (5 mL) into a cup of hot water If it bubbles a lot, it's good. If it doesn't, throw it out!
To melt chocolate safely, place in a small saucepan over another saucepan of simmering water. Stir until just melted. The chocolate, when touched to the inside of your lip, will be lukewarm.