I normally put sunflower seeds in my feeder, but decided to branch out with thistle. Even though I mostly have house finches in my neighborhood, they aren’t eating any of the thistle! I know it’s not an issue of the birds having a hard time warming up to this feeder because it’s a combo feeder and they eat from the sunflower side all the time. I’m not sure if I need to buy a different brand of thistle or if it’s gone stale? Any ideas for how to get the birds to start eating it?