I was once walking to a Tom Waits show with the 722. I had a great seat, the weather was great, it was sunny out. I was all geared up and really excited. Tom Waits! I was recording a lot of gigs at that time, so there wasn't much thought required. As I neared the venue and did my final check I realized I didn't have any levels on the 722. Given the simplicty of my rig - KC5's > cmc6 > 722, and the two independent signal paths (with no front end preamp), there wasn't much that could go wrong. The cables involved were XLR's and they were well-seated. So, panic!
After a couple minutes that seemed like an hour, I realized the problem. On the gig prior I had experimented with a low gain external preamp. That required more gain on the 722 than was available in line-in mode. So I had run in mic-in mode to supplement the gain. That meant I had used the menu to disable phantom power, a workflow I just don't do. So, enable phantom, confirm levels, and calm down. The 722 does have a phantom indicating LED, but I always had those taped over.