Machine not piercing the capsule—water leaks out the back

Hello, After placing the coffee capsule and firmly closing the capsule compartment (capsule holder), I activate the machine. The water is pumped, but it escapes behind the capsule into the used capsule container (capsule bin). I open the compartment and see that the capsule has not been pierced—neither from the front nor the back. What could be the cause of this issue?