Trouble shooting- E21 Hydraulic press brake machine ram can not come down

Sometimes when we use the hydraulic press brake with E21 controller, the machine ram can not come down even we start the machine and step the foot switch. Today we will share the solution with you how to fix this kind of problem. When we check the E21 inferface, we will see that Y is not equal to YP, X is not equal to XP. After we set the value of X and Y same as XP and YP, when we press the start button and step the foot switch, the machine will come down normally.