09/06/12 - You seem to have inadvertently angered the Thieves Guild! By Arkay and Mara, I don't fancy your predicament! There are few ways out of this problem. The first is to reload your game at the point just before the end of A Chance Arrangement, and complete it to Brynjolf's satisfaction. The second is to check whether you have a bounty in The Rift -- talk to a Riften guard and pay off any debts. The third is to wait three game days, and try chatting to Brynjolf again -- time may heal all wounds!