Yeelight offline

Install Openhab 2.4.0 on Ubuntu 18.04
I added binding-yeelight - 2.4.0.
Did a scan using Inbox -> scan.
It pops a window “Scan for Things”, and I click “Yeelight Binding”.
On wireshark, there was a response from the yeelight.
However, on Config->Things it shows offline.
Please help, I am new to home automation.