Cameron Files...Loch Ness...Help

I've played through the game and double checked my actions against two walkthroughs. My problem is that I'm stuck at the three circular rooms that are the chem lab, McGrab's room and the room where MacFarley is held captive. I've followed all the correct steps including turning the wheel on the back wall of McGrab's room...and still when I walk to the central pillar, the buttons for the other two rooms are inaccessible. Can someone please help?
Thanks

The views here are very confusing; I suggest at each node, turn carefully and look for an alternative exit. Some of the exits are very narrow and hard to see.