Waterfowl have a different scent than upland. Once, while quail hunting, I dropped a Snipe. It dropped in some high grass right in front of us and we had a pointer and setter follow the mark and sniff around forever and a day. Neither one of those dogs was interested.
Sounds like your dog is making good progress as she is taking to the feather. Now, go buy yourself a live duck. Take it home, shackle it's feet, cut its flight feathers, and bind its wings. Toss it out, see what pooch does.
If she balks, no big deal. Don't scold her. Put her away and then ring that ducks neck and throw it in the freezer.
Day or two later, take that duck out of the freezer about a two hours before you are ready to work. Toss the duck out and do your level best to get that dog stoked up and convinced to pick up the dead duck.
If she won't, no big deal. Just put her up, put the duck back in the freezer, and try it again another day.
If she does, then repeat this for a couple of weeks until dog is very comfortable with the duck. She should actually become quite excited when the duck comes out of the freezer. After a couple of weeks, brocure another LIVE duck and start back at square one. Throw the shackled duck out and see if she picks it up. If she does, work with that awhile. Next, unshackle the wings, just the feet shackled. Will she still pick it up when the wings are flapping? Yes, good deal, no, keep at it. I guess the final step is to unshackle the duck's feet, but make sure you put your running shoes on for that! Dog might be convinced to take hold of that live running duck if you are trying to chase it down too!
If all of this fails, and you become impatient with the process or the dog, Force Fetch the dog. It might sound imposing, you might not think you can do it, but I am here to tell you, it is an EXTREME shortcut that WILL get you and your dog from point A to point B (retrieving machine). It really isn't that tough, and it isn't really that FORCEful of a process.
Just my opinion....
WHAT'S UP MIKE???!!!??!! How's your season coming along?
"I'll start spending less time with my dog and more with my wife when she starts fetching ducks for me"