Explanation
Pg 70: "after you add and register a FortiGate device with the FortiAnalyzer unit, you must also ensure that the FortiGate device is configured to send logs to the FortiAnalyzer unit."
https://docs.fortinet.com/uploaded/files/4614/FortiAnalyzer-5.4.6-Administration%20Guide.pdf Pg 45: "ADOMs must be enabled to support the logging and reporting of NON-FORTIGATE devices, such as FortiCarrier, FortiClientEMS, FortiMail, FortiWeb, FortiCache, and FortiSandbox."