@victornguyening Most likely is that the firmware on the Duet 2 and PanelDue are out of sync. Send M115 in the console in DWC and post the response, and go to the 'Setup' screen on the PanelDue, and the firmware version will be reported at the top.
Also check your config.g has M575 P1 S1 B57600 to enable support for PanelDue.
Ian