Akai S1000 / S1100 samplers

Being a new comer to the world of Akai samplers I find myself puzzled 
by many aspects of the operating of my S1100. I have reached a glitch 
in keygrouping specifically, the problem is...........

When I'm on the Keygroup [KGRP] page and I have to create, say, three 
keygroups for 3 drum samples, the sampler does not appear to want me 
to be able to change the [change number of keygroups] from 1. I know 
that it can't be done from the data knob and that the '+' button must 
be used but that number won't shift from 1 for love, money or pleading 
with it...........
Where I am I going wrong? Can someone reveal to me the answer?

Cheers.