If your sauce 'slides right off into the water pan' it is because it has too much water in it (relatively speaking). Take some of your sauce and put it in a small pot; put it over medium heat and let it simmer then reduce to 1/2-2/3 its original volume. It should be quite thick. Then, if desired, add a touch of honey. Mix well, cook 1 minute or so, then pull from the heat.
Paint on your chicken several minutes before pulling from the grill/cooker. Don't glob it on--paint it on with a brush, on the thick side if you wish, allow a minute or two for it to seize, then paint on more if desired, allowing it some time to seize as well.