Hi Glenn,
I apologize for the long delay with this response. I have not been on this site in several weeks. I agree that your feeder shouldn't be in direct sunlight. It isn't a definite no-go, but placing the feeder in the sun will cause your nectar to go bad much faster. If you keep it in direct sunlight, I'd definitely recommend putting far less nectar in it and be prepared to change it out about ever 2-3 days.
As for placement, don't blame the birds for going for real flowers. After-all, that's what they do. Placing the man-made feeder in a conspicuous location where they can see it (often near real flowers) is a good way to get their attention. I keep my two main feeders under a crepe myrtle tree because it keeps the feeders in a fairly visible location, but also keeps the feeders in the shade, keeps them near my potted cigar plant, AND gives the birds a place to perch between feedings. The birds DO like to have a place to perch...if you can position your feeder near a tree with small branches and places for them to perch, they are more likely to use your feeder, because they will have cover AND not have to fly so much in between feedings.
Lastly, a water source helps too. If you have a shallow bird bath that a hummingbird can land on and splash in, that can help. Likewise, I learned just this year how much they enjoy misters, so I placed one in the same tree near my two main feeders and they LOVE it! They fly through the mist and rub against the damp leaves for a bath when they roost.
Here is the good news: even though it is getting late in the season, and many hummers will soon begin migrating south, "IF" you can get them to take notice of your feeder, they will remember it next spring. Hummingbirds can recall up to 40 or 50 different food locations in a geographic region. They make a mental map or "trap line" that helps them sustain their activities even if a few food sources disappears or is too crowded with aggressive hummers. So, if they can make note of your feeder now, they are very likely to return next year.
The trick is to keep the feeder someplace where they can find it and keep the nectar fresh and clean.
Hope this help.