The records access officers upon denying access to a request for records deemed exempted from disclosure by the law, shall explain in writing the reason for such denial. The written denial shall advise the person requesting access of his or her right to appeal to the individual designated to hear appeals. Upon failure to locate records, the records access officer shall certify that the agency is not the custodian for the records, or that the records of which the corporation is a custodian for the records, or that the records of which the corporation is a custodian cannot be found after diligent search.