It is possible that a search doesn’t provide the information you’re looking for. There are several factors that could be producing these results.
It’s important to double check the spelling of a name, as well as trying nicknames or common alternative names in your search.
Also, public records are created and edited by humans. Human error can lead to incorrect information that may be replicated across different systems and enter public domain. It’s also possible that in some situations new information has yet to be associated with a person.