From the Ops Center proxy, try to SSH to the IP of the asset with the provided credentials and run "zonename" - did you get "global"?
Ops Center requires the Global zone to be managed before the zones under. Also, depending on the discovery method you used, you may see a misleading name in that tab.
The best way to do this is to choose "Custom discovery" in 11g, or "Add Assets" in 12c and provide the specific IP of the global zone. This will guarantee that you are indeed trying to add the global zone.
Some more thoughts - if you're using 11g to discover s10s_u10 - you may be running into an issue with the /etc/release - try changing it to u9. Also, try running the latest OCDoctor --agent-prereq on that global zone.
Last - since you just installed, I would strongly recommend moving to 12c (Update 2 is already available) which has a tremendous amount of bug fixes.