Calling PLSQL function and raising exception

I am attempting to insert a custom Controller in an OA Framework page.  I have written a controller that extends the seeded controller and intend to add some custom functionality before calling the original controller as super.

I wrote a PLSQL function to carry out the validation then run it from the controller.  I can tell from debug logs in the PLSQL process that it is being called and is returning the expected value ( in this case "FAIL"), but nothing is happening on the screen.  It appears the exception is not being raised.  Here is the code (Note rpos is declared as int and has a value of 1):