The two systems are totally incompatible (one is 1-line; the other is 2-line) - the 6000 will only work with its triangular base station/charger (at least here in the states).
Hmm - if you push in that button for several seconds and the red light doesn't flash, yes, that's a problem. Another way to put the base unit into registration mode is to use the handset to re-set it (press dot-70008-then ok). But you can't do this since none of your phones are registered to it.
Hopefully someone else will chime in.