After the Sins of our father level there is a part where you are traveling on a platform with tons of air creatures. Once you make it to the other side you fight a few guys and then boom nothing. After spending about 10 minutes trying to figure it out I watched an online video and there is a lever that pops up when you kill the last guy... I have reloaded it three times now and it's not popping up....ugh what the hell?

That's Dante's Inferno for ya'.
 
Not sure what to say unless you have an earlier save that you can go back to.

Fourth time is the charm...it worked that time... wow buggy :(