Tolkein estate, meet Hollywood accounting.
The only thing in this world more mythical than hobbits are residuals in Hollywood.
Hopefully the Tolkien estate has it in writing that royalties were to be paid on GROSS profits (or some such).
I read some time ago that the author of the Silence of the Lambs got zilch because the contract stipulated it would pay only if there was a net profit... wa-la no net profit so the author got nada (or relatively little).
Hollywood = sleaze-ville.