How are you turning the valves on and off manually? By opening and closing the bleed screw on the top (correct way), or by opening and closing the volume control handle on top (incorrect way)? Also, are you running just one valve open at a time?

Thanks for the reply, but I found out what the problem is, malfunctioning valves. I was turning the bleed screw but it was still not closing the valve. When I called Orbit, they told me to unscrew the bleed screw and tighten the black the small black cap that holds the bleed screw (they informed me that sometimes these screws are not fully tightened when they leave the warehouse, but apparently there must quite a few like this as four the six valves were like this). When I checked the screw it was tight as can be. I went to the store and bought a new box and these valves work. They offerred to send me a replacement diaphragm but it would take 5 days to recieve it. I declined.

Hey, just wanted to let you know I had the exact same problem. I made my own manifold, hooked the garden hose up to it, and tested every valve, and they all worked perfectly. I let my system run on the garden hose for about a week with no problems. Then (after I buried the valves and the box) all my orbit valves decided they didn't want to close anymore....manually or electronically. I had three hunter valves on the manifold too, and all those still work ok, but I had to take the orbit valves back to the store.