Why Isn't My Pendulum Answering As Strong As Before?

ok. yesterday when i held the pendulum (rose quartz) and an amethyst one in my hand to pick the right one for me, the rose quartz one started vibrating and my hand started shaking, so of course i got that one. all of its answers it made very wide circles, but it really only worked if i thought the questions at it. then, i gave it to my reiki master and she charged it with the moonlight, since last night was a full moon. now, she gave it back to me this morning, and it's answers are all so feeble! does anyone know why this is happening? did i choose the wrong pendulum?