I am trying to figure out how to open the solenoid valve properly. I switched my lab's power supply to 12V and hooked up the solenoid valve with a 12 fl oz bottle 3/4's full of water to create enough pressure, but the valve still doesn't open. Only a few drips of water come out and the power supply drops to about 7V. What is it that I am doing incorrectly? Is this amount of fluid enough pressure to open the valve?