You should do that：
1. Make sure your laptop's USB C port supports DisplayPort/video output.
2. Check your HDMI cable and monitor. (Connect the monitor to the laptop directly, see if it works)
3. Provide sufficient power supply from the USB C hub.
To better and faster solve your problem,please click the related article to solve it:
👉 https://mokinglobal.com/blogs/hub-adapter-1/decembers-top-3-usb-c-hub-series-faqs-unveiled
👉 https://mokinglobal.com/blogs/hub-adapter-1/solved-usb-c-to-hdmi-adapter-cable-not-working
👉 https://mokinglobal.com/blogs/mst-hub/why-isnt-my-hdmi-port-working-troubleshooting-tips-from-mokin
