Creating comms on Jupyterlab V4

Hello, I want to create a comm for my extension to have communication with my kernel.
But sadly, the backend gives this error:
IPKernelApp] WARNING | Unknown message type: ‘comm_open’.

For frontend part, I also am not able to use a proper way to have a comm. I tried this: Comms — Jupyter Notebook 6.5.2 documentation but ‘Jupyter’ was undefined, so it was also not successful.