Yeah, Brynjolf should tell you to talk to Maven Blackbriar which keeps the quest moving forward. I believe that was one of the quests fixed in the 1.04 patch. If your game isn't updated, download and install the patch, and then let your game run for ~15-20 mins. The quest should start automatically (or you may have to initiate dialogue again, I'm not positive as I didn't have the issue personally). Per the wiki: Welcome to the site by the way. Let us know whether or not this resolves your issue. If not, we'll try to help you out by trying some alternative method.