Bt Synergy 2110 Wont register to the base unit?

I can't get my phone to register to the base unit, After i hold down page, press options 5/1 it should beep and then i should be able to enter my pin but it doesn't do anything. The New Call light is also continually flashing on the base, but not showing on the handset, i can't get it stop flashing. Don't know if this is maybe what's causing it not to register?

Anyone have any advice on how i can maybe reset the base unit or something? I've tried the obvious unplugging etc but no joy.

Thanks.