Surface RT 2 1572 model

I am in the process of replacing the screen and digitiser assembly on my Surface RT 2 1572 model. The new assembly arrived with a new, separate main, central ribbon connector. Is it essential to use this new ribbon connector when fitting the new assembly or is it simply a spare? I have used my original ribbon (still attached to the motherboard inside the tablet) but although power and content appears on the screen there is no operation by touchscreen method ie there is no response to touch by finger. It works fine when a keyboard is plugged in, however. Can anybody help, please?