problem with Apple Cinema Display

My Apple Cinema Display (30") was working fine yesterday. Today, whether I attempt to connect it to my Air (13" 2012 10.7) or my Mini (2012 10.8), I get the same result: nada on the monitor, although it is recognised on both machines in my USB tree (About this Mac -> System report -> USB, and I see it there on the list of devices). It's not "working invisibly" i.e. backlight problem, because I can't drag windows onto it, and my menu bar doesn't hop over to it as it does by default usually. Power is connected (the light on the front is on). I'm using a dual-link adaptor (mini display Port and USB connectors). I've plugged and unplugged all the components many times, with and without power. The main display on the Air goes solid blue for a second when I plug the ACD in, but when it comes back it's the same as before--the ACD doesn't come to life. Is there anything else I can try, short of taking it to the store? Oh I also reset the SMC. Thanks.