Debut won't recognise my webcam

[birdlover]

I recently bought two usb web cameras to view birds with (one is fitted inside of a nest box) and the other camera is to view my bird feeders. I attached them to a usb extension cable to my macbook pro which runs on the OS X Yosemite operating system.

 

Sometimes I get a video view from the webcameras back to debut, but it keeps cutting out and the camera screen vanishes with a message appearing from Debut saying 'No device of this type is present - please try again'.

 

I try unplugging and checking the USB connection and the settings and it takes ages to try and get debut to recognise the camera device and I feel like giving up.

 

What should I do?