If the bottle is leaking all of the water out, there is a problem with the bottle. With the typical ball-and-tube style of bottle, a few drips are normal right after it is filled, as it depends on a vacuum to hold the water in and some loss occurs as the vacuum is created. But once the vacuum is established, the only loss should be the occasional drip as the water warms up (during warm weather) and maybe a little right after the rabbit takes a drink. It can be a little tricky to find the right angle for the tube. If the tube is sitting at too shallow an angle (too close to horizontal) it can drain itself, as bubbles come up the tube and a vacuum never really forms. If there is a leak at the bottle/cap connection, the same thing can happen.
I don't know why your rabbit would have a problem with a dewdrop valve - they are functionally so similar to a bottle with a tube, most rabbits can transition from one to the other without issues. I have a water system in my rabbitry that involve water valves in each cage, and if for some reason I have to put a rabbit in a cage with a bottle, they switch over as if there was no difference. Are you sure the valve was functioning correctly? Just like a bottle with a tube, if you tap the end of the valve with your fingertip, it should get wet as a few drops of water come out.
I don't know why your rabbit would have a problem with a dewdrop valve - they are functionally so similar to a bottle with a tube, most rabbits can transition from one to the other without issues. I have a water system in my rabbitry that involve water valves in each cage, and if for some reason I have to put a rabbit in a cage with a bottle, they switch over as if there was no difference. Are you sure the valve was functioning correctly? Just like a bottle with a tube, if you tap the end of the valve with your fingertip, it should get wet as a few drops of water come out.