Tuning the function result cache

I am using Oracle 11.2.0.3.  I have set up the result cache and written functions to use the result cache.  One of the functions relies on ALL_SA_COMPARTMENTS; the documentation says you should not use anything owned by SYS or SYSTEM, and ALL_SA_COMPARTMENTS (and everything it depends on) is owned by LBACSYS.  The issue I am having is that there are a LOT of invalidations going on, and sometimes the cache returns the wrong results, perhaps because the result has been marked as invalid. I thought that when a result was marked as invalid, Oracle would then execute the function to