connecting ddjt1 to serato

right so im trying to get my ddjt1 connected and working with serato everythign should be working but somehow its not . the cable are all plugged in correctly the light are on when i plug the usb cable to the computer the deck react how they should lighting up and flashing but i go to try use the decks and it dosent effect the doft were . it like it not even plugged in . i cant work out why and cant find anyone/were that can help