xStick "Error discovering neighbors of <MAC Address>" in XCTU

I use XStick USB Adapters with XCTU to create a XBee Map for my SmartThings network according to this article : https://community.smartthings.com/t/faq-mapping-your-zigbee-network-with-digis-xctu/28477

At first, it works great but after I pressed the “Load default firmware settings” by mistake, it’s LED stop blinking. And every time I tried to “Scan the radio module network” the error message "Error discovering neighbors of " popped up stating “Cannot find the local device address”

What’s wrong with it and how to resolve?

I’ve learned that it was because the xStick didn’t register to the SmartThings’ ZigBee network. So I’ve to try making it registered properly and then the xStick’s LED will start flashing after the registration process has completed.