* The name is misspelled. You may want to double-check the spelling.
* The person is not well-known. There could be many talented individuals who haven't achieved widespread recognition.
* The person has a different stage name. Some performers use different names for different projects.
To help me find the information you're looking for, please provide:
* Any additional details about Sheila Helpmann. Do you know anything about their profession, nationality, or time period of their work?
* Is there any other information you can share about the movie or television project? For example, do you know the title, genre, or year it was released?
With more information, I can hopefully help you find the projects you are looking for.