It is odd. I had the same issue with bronze studded helm. So I just moved on to the bronze studded boots, which worked fine. not sure whats going on here. (I did have to change the CraftedItemIDs for all of the studded stuff in the db, they're all wrong (down in the 700s range, where the client expects them to be up in the 5000 range - and had to set the crafting type from 2 to 11 {Tailoring NOT armorcrafting]) However I'm using an older, much customized db which I'm not willing to overwrite with one of the newer ones. Also using a slightly older DOL build (1.9.7.35823) since most things are working, I don't want to break it
Short Answer, I don't know why crafting works for some items and not others...