Let's step back a bit. First, what hardware are you installing on? Is it a supported platform or is it some guest VM? (That might contribute to the problems).
Next, after you installed Solaris 11, did the system boot cleanly and all the services come up? (svcs -x). If it did boot cleanly, what did 'uname -n' return? Do commands like 'getent hosts <your_hostname>' work? If there are problems here, Solaris Cluster won't be able to get round them.
If the Solaris install was clean, what were the results of the above host name commands after OSC was installed? Do the hostnames still resolve? If not, you need to look at why that is happening first.