I'm having a weird problem where it doesn't recognize that any of my characters have the Cooking - Mithril Headed Trout recipe. It is in the recipe list window, but when I examine one of the actual recipes it says it's learnable by characters that already know it.
(Actually reading some other posts - this is probably the issue where the recipe name does not match the item. It creates "Mithril Headed Trout", but the recipe is "Mithril Head Trout")
I've also seen the attempt to index field 'headers' (a nil value) error mentioned earlier in the thread sometimes (happens upon opening a tradeskill window).