Soloing Uldaman (getting to Archaedas)

I'm struggling!
I can pretty much walk through Uldaman and kill everything in sight but I've one quest which is really annoying me: Restoring the necklass.
I need to get the power source off Achaedas but I can't get to the bugger in the final chamber!

I can get to the door but, after killing the scorpids and saying hello to an Enchantment trainer (can't remember her name) I'm confronted with a locked chest and no way forward.
What am I missing? What should I be doing??
Kana

I have no idea. I hate that place. Don't you need a certain number of people to summon the stone guys and kill them then onto the next room?

Well yes taeriss is right, you need two other people to help you activate the giant stone guards, and after defeating them the door opens, you also need them to start the final boss encounter.

man even having not played wow for a week, i somehow get to be a wow geek. yai me

i'd like to help you on that :p