Registering handset?

I have the binatone symphony 2210 5 handsets. I now want to use just two of the handsets in a different location but am having problems registering them. I have deleted all handsets bar the main one which says sharon 1, the rest says unregister and do not work. I have tried to register them it asks for pin which I put in 0000 and then shows wait and then with unregister. Could someone please help.