Yep, mosttimes you need a second requirement like character level or a special crafting level.Think I figured it out....need character levels it seems. Thought it was just going poof.
Hovering the mouse over the locked symbol mosttimes show you more information.
And don't forget when you die, you attribute's are lowered for a while, then it can happen that you can't craft something anymore you could or at a lower quality.