So, this makes twice now that I've run into this problem and I'm about fed up.

I've finished all 4 "special missions" for the thieves guild. Completed "Darkness Returns". And even have all my Thieves Guild armor.

Yet, still, I am unable to get "Under New Management" to start.

I've even killed one of my fellow guildmates and paid my dues in hopes to get it working (idea sparked by the UESP wiki).

Does anyone have any idea how to get past this?

Fool me once, shame on me. Fool me twice...you have alot of unresolved bugs to fix.

Could check here to see if there is any possible fixes. I've yet to do the Thieves guild as I don't need that kinda problem popping up after hours of running back and fourth. Maybe someone else that has done the Thieves guild can help more.

http://www.uesp.net/wiki/Skyrim:Under_New_Management

"I've even killed one of my fellow guildmates and paid my dues in hopes to get it working (idea sparked by the UESP wiki)."

Tried that.