It's possible that:
* The name is spelled incorrectly. A simple misspelling could be the reason you're not finding any information.
* The person is not well-known. There are many actors and actresses who work in smaller projects or have not achieved widespread fame.
* The information is not publicly available. Some people in the entertainment industry choose to keep their professional profiles private.
To help me find information, could you please provide:
* Any additional details about Sue Costin, such as their age, location, or any other projects they might have been involved in?
* Any other information you have about the projects they might have been in.
With more information, I can try to track down the information you are looking for.