It's possible:
* The name is slightly misspelled: Perhaps you're thinking of a different name like "Robert L. Cruben" or "Robert L. Craddock."
* The author is relatively unknown: If the author has published independently or in niche genres, they might not have a strong online presence.
* The name is associated with a different type of work: It's possible that "Robert L. Cruden" is a name associated with academic research or other fields outside of published fiction.
To find the author you're looking for, please double-check the spelling and provide any additional information you may have about the author or their works.