Ah, that's your problem, debuff = aggro..sometimes huge aggro. :P
I have 2 keys set up for building aggro on my SK. First key is a normal taunt by itself.. all other toons have this key set to assist the tank..nothing else.
Key 2 is my oh-crap-get-aggro-now key. It contains anything that can increase hate, and then some other AoE stuff too, just in case. All other toons have a macro with any spell/ability they can use to dump aggro.