Touch pad not working at full range

I have 5 Gliss and one of them does not send voltages in single slider mode until the finger reaches almost half of the touch pad. So for example if I open a vca with it, it will start opening it almost halfway through the touch pad. This doesn't happen with the others. I've tried calibrating it with negative results. ¿Is there something I'm not doing well? ¿Is the device not working properly or is it me that is not configuring it correctly? I've tried many things, like setting a custom range manually and adjusting sensitivity, but it still does the same thing. I have it set up just like the others but it just doesn't work properly.