I love hummingbird feeders! My parents have had them set up for years around their houses. I also have one, and a few hummies which hang out around my apartment but for whatever reason, they refuse to stop at my feeder. Maybe there is just more than enough food for them that they can't be bothered flying up to the third floor!
As long as the sugar dissolves into the water it should not be a problem. However DON'T add the red food coloring. It does not do the birds the slightest bit of good.