How to Troubleshoot 'setOperateMode Failed' When Calling the SDK?

Cause 1: SDK example code defaults module ID to 1 — it must match the actual module ID (in case the customer has changed it)
Cause 2: The 120-ohm DIP switch on CANable (EYOU USB-CAN debug board) must be switched to ON beforehand (otherwise communication may fail and trigger the error)