Originally Posted by Axel 360
Delvin wont buy the Left Eye of Falmer from me, wich is the last special trinket in the Thieves Guild Main Mission you will get. Pretty annoying.
I just had that happen too (second play-through v1.1). Happily it's not a big quest breaker. Did you already do all the extra jobs to bring the guild up to full strength?... I did, and was wondering if that might have caused it. This did not glitch for me in my first play-through, and there I did not do all the extra jobs to bring the guild up to full strength until after I finished Darkness Returns.