Fletching combines not working
 

When I try to combine the appropriate combines for any arrow, I get the "you cannot combine these in this container" message. Nothing is stacked or anything like that. I've been making class 2 bone hooked arrows for months now, to make them requires a 1 hooked arrow head, 1 bundled bone arrow shaft, 1 several parabolic cut fletching, and 1 small groove nock. I was making them fine a few days ago but now when I try to combine, nothing. =(