Dark Brotherhood problem

[Anarchy Nooblet]

Forgive me if their is a topic already about this but I did search and could not find any threads precisely like my problem, mainly due to the traffic I got. Anyhow, I was attacked by them once, took everything he got. Went to the nearest guard....and can't find the option to tell him about the attack. No matter with what guard. I'm level 32, beat the main quest and the Bloodmoon quest line. On top of this, no matter how long I wait, what time of day, how often I do it, I can't seem to provoke another attack. Also I'm using the xbox version so console commands aren't useful for my situation. Any help would be greatly appreciated.