Hi guys, I've been training my girlfriend and she's having problems with any type of squatting movement. Her left knee always buckles inward while raising the weights. We've tried lighter weights but unless the weights are ridiculously easy for her it still seems to happen. Any advice? I don't know what to have her try next. She really likes the training and doesn't want to stop. In my opinion her form looks perfect (other than the knee issue, of course).