It's possible that:
* The name is misspelled. Double check the spelling.
* The person is not well-known. They might be a lesser-known actor or have worked on projects that are not widely known.
* The person has chosen to keep their work private.
If you have more details about Nicolas Quilter (e.g., roles they have played, specific projects, or where you saw their name), please provide them. I'll be happy to help you find more information.