Unfortunately the 1000, 1000b and 2000 boxes use a strange remote control protocol which is incompatable with most remote senders.
The solution is either to get an expensive remote sender which is compatible (there are some, but I can't remember the models off the top of my head), or use a Red Eye device. This translates ordinary remote control signals into the funny IrDA ones that the 1000 and 2000 use. You can find out more, and order one, from
www.redremote.co.uk, but basically this would allow you to use any old remote sender you like.