When nothing is found
Check identifier accuracy and format. If there are no mistakes, record that this query produced no available result. That limited conclusion does not establish the absence of a person, account or event.
When there are too many results
A common name or broad range may fit multiple people. Refine only with details you reliably know. Adding a guess just to shorten the list may exclude the relevant record.
When records disagree
Compare time context, sources and original identifiers. They may concern different subjects or periods. If the disagreement remains unexplained, keep the records separate and avoid a categorical conclusion.