That error means that the iCamSource is having problems communicating with your webcam.
Are your webcams plugged into a USB hub or extension cable? If so, please try plugging them directly into the computer.
What are the Models of the three Logitech cameras?
Also, please make sure there aren't any other video capture programs (such as Skype) running. They might be fighting iCamSource for access to the camera.
If possible, send me a screenshot of the iCamSource window so I can verify the settings.
For more information about the Error Code 14 please see this forum post:
http://skjm.com/forum/index.php?topic=174.0