Is it OK to dock a nonexempt’s salary if the hours just aren’t put in?

Q: “We have a nonexempt salaried employee who is required to work 40 hours a week. She rarely works overtime, but when she does she gets 1.5 times her hourly rate. My question is, if she works less than 40 hours in a week, does not have any PTO left and does not make the time up, can we dock her salary?” – Maria, West Virginia