There can be several reasons for this. If you are using skin care products that contain salicylic acid, glycolic acid or alpha hydroxyl acid (AHA) of any kind, these can cause the skin to lift while waxing. Another cause is aggressive exfoliation such as microdermabrasion or chemical peels. Prescription medication such as antibiotics, accutane, retin-a, renova, strivectin, proactive and avage can cause thinning of the skin which results in lifting during waxing. My recommendation is that if you are unsure about what you are using, just ask. But it is still difficult to predict how every skin type will react no matter how many precautions are taken.