Flash1707822794

I have a Hornby Select controller it works perfectly with the decoders I use . Appel . But for some reason I can not use number 2 it says the loco is programmed with the number but then the 2 starts flashing and will not work I program the loco chip with a different number and is fine. I am the type of person that it all has to be in order. So this silly thing bugs me a bit... any idea out there thanks.