When we pray in His name, we are praying His will as if in His stead much like when we act on behalf of a loved one in a power of attorney situation. Our prayers are answered in the affirmative only when they are in His will. Sometimes our prayers are answered differently than we petition and when that happens, it is for our good. Our Father knows what is best for us and will answer with a yes, no, or with a different result than we petitioned.