if you have a dazzle, then it might not work with vdub. but if not go to the device tab and make sure you chose your cc as the device. if its not one of those 2 things then i dont know.
Go to video then click preview. Restart vdub and do that again if it isnt already ticked off. Make sure ALL cords are pushed into where they should be, and restart your computer if nothing above worked.