my tool wont fit
 

I am uninstalling my camhousing and there are a couple of 11mm bolts which I cant take out. My 11mm socket just wont fit in the hole!!. were the wrong nuts used?

Are any of the nuts barrel nuts (wrenching hex is on the inside)?

nope

Three of the 20 nuts securing each cam tower to the heads should be the barrel or cylinder nuts with the inside hex wrenching feature. As you have found out this was done for tool clearance reasons. Someone in the past has apparently installed regular hex nuts in all positions (the cylinder nuts now cost $2 or $3 each); to do this they either made a special socket or tightened them by some other "provisional" method.
You are going to likely need to make a special, turned down socket to remove; try starting with a 1/4" drive socket. Good luck.