Anything Goes : Question about Legal rights by Tui Allen

My agent sent my novel, a story of prehistoric dolphins, to a film-maker here in New Zealand some months ago. My agent was one of this country's most respected literary and film agents, responsible for some of our best known books and films, such as Whale Rider, for example. The film-maker loved the story and wants to make an animated feature film of it. (There is now a lot of technology and know-how in this country for this.) He and I have been discussing it by phone and email ever since. But he has had other projects under way also. I had another call from him tonight. He is now at the stage where he's wanting to to get some sort of legal stuff sorted out. But the sad thing is, my agent has since died. He was aged 92. He would have been the person who would have helped us to sort all this, I'm sure. But the film-maker has been talking to a lawyer and the lawyer has asked him to be sure I have the legal rights to my book, before making contracts etc. I wrote the story, entirely out of my own imagination, and did not sell the rights to any commercial publisher. EXCEPT! I did sell the rights to a publisher in the The Czech Republic who has translated and just recently published it in that language in the Czech Republic and Slovakia. That contract was negotiated by my agent just before he died. Other than that, I have only self-published in both e-book form through Amazon kindle, and in print via Amazon's Print on Demand facility, Createspace. So does that mean, that as far as making a film is concerned, I am the holder of the rights to my book? It is entirely my own original work.