There is a puzzle with 4 rotating stones in a flooded hallway. I solved that no problem. What I'm having trouble with is the next area, with the body of archmage Geirmund. I grabbed the key next to his body, opened the door and went upstairs to pull the lever to make the bridge come down. Instead, spikes shoot from the wall and the bridge won't come down no matter what I do.
Is there something I'm missing here? I already killed the draugr that was on that platform with the two raised bridges. What do I do to progress?