In my quest to reduce vertical space and advance my perl horizon :^) I am trying to convert my subroutine return statements to use the ternary operator.

If you're having problems "optimising" your code with the ternary operator, perhaps you should avoid doing so until you truly understand how to use said operator, lest your "optimisations" decrease your code readability and maintainability (and, as seen here, its "workingness" :)).