There could be a few reasons why you are experiencing this issue. Here are a few things you can try:

1. Make sure that the camera is properly connected to the EZ-B v4 and that the EZ-B v4 is properly connected to your computer.

2. Check that the camera is compatible with the Camera Device skill in ARC. You can find a list of compatible cameras on the Synthiam website.

3. Try restarting both the EZ-B v4 and your computer.

4. Make sure that the camera is not being used by any other programs or applications on your computer.

5. If none of the above solutions work, you can try reaching out to the Synthiam support team for further assistance. They may be able to help you troubleshoot the issue.