It might take a few days for them to work the feeder, or if there is good nector in the area - they may not take the feed at all. If there is a good nector flow, then the bees generaly take the natural stuff and leave the feed alone.
Three of my 7 hives this year did not take any feed for some reason this year, but they are working and growing. Often I have found that my bees don't read the same books I do, and do what they want on their own.
Other things to attact them to the feed, is adding some essentiol oils. They sell that honey bee healty, or you can just add a few drops per gal of peppermint oil or lemongrass oil. I assume you are feeding 1:1 or 2:1 sugar to water mix.
Also generaly when using a top feeder, you may not want to put the inner cover on. I use the top feeders from Mann Lake and the tell me not to use the inner cover.
good luck, and welcome to being a beek!!!!