can't seem to work my astra key fob??

Hiya, weve recently purchased a Vauxhall Astra,1.6 2000 and brought a new battery and thought it would work but no. The red light or any light does not appear on the fob and we are not sure if we need to buy a new key fob altogether. I've tried the ignition, holding the lock/unlocked button for 10 seconds to reset it but it still doesn't work. Not sure if their is a part missing inside or something. Would be grateful for some help. Thanks