During team practice, my partner missed her first serve. As she prepared to hit her second serve, a ball came rolling onto our court. Three players began calling a let, trying to get the server's attention. For whatever reason, server did not hear this commotion and hit her second serve. How should this be handled? Obviously if a ball rolls onto the court when server has already started her service motion, she takes two serves. What if the issue is the server didn't hear everyone trying to get her attention? In that case, is it just one serve?