The IPC-Color4K-T180 might not have a manual light control option in the DMSS app like your PTZ cameras. Some fixed cameras with built-in lights only turn on automatically in low light or when specific settings like Smart Illumination are enabled. Check the camera settings in the NVR or web interface to see if there's an option to enable or adjust the light. If no manual control is available, the camera likely manages the light automatically based on its settings.