There's nothing particularly special you should need to do. You would need to have the pss and pnoise analyses enabled at the same time, because the pnoise analysis must run after the pss in the same invocation of the simulator.
What subversion are you using (of both virtuoso/ocean and spectre?). In virtuoso/ocean you can type getVersion(t) to retrieve this; for spectre it will be in the output log.
Maybe you can share the entire OCEAN script? Maybe you can show the corresponding analysis statements from the bottom of the input.scs? Where exactly does the error occur (i.e. what is it doing at the time)? (some context would help here).
There was a problem in the past with using hierarchical (i.e. not top level) nodes for the positive/negative outputs from pnoise, but I think that was solved quite some time ago.