It sounds like you don’t create a proper seal at the base and then don’t pump high enough for the suction to stay intact. You shouldn’t tilt the cylinder at low vacuum pressures or you destroy the seal. Lay down and hold the cylinder vertically in a 90degree angle to your body. In my experience once the pressure is stable at -4-5inhg the suction should be so strong that you can stand up with it. Nevertheless, I always support the cylinder with my hands so it sticks out instead of bending my penis downward.
