Hi Hubert, we're sorry to hear you are having trouble with your chair mat. There are a variety of reasons the mat could be sinking under your wheels. First, please make sure the carpet pile is no more than 1/4 inch deep. If it is more than 1/4 inch, the depth of the pile exceeds the cleat length and the mat will not be able to create a smooth surface. When a mat is first placed on a carpeted surface, it does take time to settle into the pile. The cleats need to work their way into the nap of the carpet to keep the mat in place and to create a more solid surface. To speed up the process, it can help to place a piece of cardboard over the mat and place heavy objects on top and/or walk over it to help embed the cleats. If you continue to experience the issues, please contact us at customersupport@dimexcorp.com.