it may be because the CDC driver is not installed on your PC, or the proper virtual COM port was not selected after installing the driver.
Note: On Windows 10, the driver will be installed automatically when the camera is connected.

CDC Driver Installation Procedure

Please follow the steps below to install the driver and connect the camera:

If you did not change the installation folder when installing KSACtrl, the driver files are copied to:
C:\Program Files (x86)\Sentech\KSACtrl

1. Stat the driver installer located at:
   C:\Program Files (x86)\Sentech\KSACtrl\cdc\dpinst_xxx.exe
   For 32-bit OS: run dpinst_x86.exe
   For 64-bit OS: run dpinst_x64.exe
2. After the CDC driver installation completes successfully, connect the camera and PC with a USB cable.
   The camera driver will be installed automatically.
   It may take several minutes for installation to complete.

Once the driver installation is complete, disconnect the USB cable from the camera, then reconnect it to the PC.
From this point on, the UVC camera will be recognized correctly and can be operated from both the UVC Viewer and KSACtrl.