It's possible that:
* The name is misspelled: Double check the spelling and try searching again.
* They use a different name professionally: If you have any other information, like a specific role they played, that might help narrow the search.
* They are not a public figure: They might be involved in independent projects or have a career outside of the entertainment industry.
Without more information, it's impossible to say for sure if Christa Fast has worked on any movie or television projects.