Just follow the instructions as far as letting the sun charge these up for about 3 days before use...they work great! Just one thing...the instructions say to turn the dial to the sun icon setting ( * ) if you only want the unit to trigger at night. But of course this is a misprint. Instead, turn the dial all the way to the crescent moon icon to make this unit only trigger at night. Keeps from wasting the battery energy during daylight anyway. I love these..so easy to set up, and not have to wire anything! Bright too.
UPDATE: I have had these for about 2 years now. They are STILL working great! No issues with water getting in them and making them stop working, etc as others have said. Mine have been 100% waterproof. The ONLY issue I've had with any of mine (and I have 9 of these lights) is that on one of them, two LEDs have burned out. But honestly just those two LEDs don't make that much of a difference to the overall light output from that one light...I'm still using that same light (2 years later) and it puts enough light just fine (sans the two LEDs).
I don't understand the issues others have said on here...maybe you just got a bad batch off the assembly line? Not sure. But I'm a happy customer with these lights!