New earfun uboom won’t stereo pair with old uboom

I just received a new uboom which I wanted to stereo pair with my old one. Both are SP200.  I followed the instructions: 

1. turn on one union and connect to my phone

2. turn on new union and hold the Bluetooth button for 5 secs and wait for flashing to stop and both to connect. 

But this doesn't happen. One union stays connected to my phone and the other just keeps flashing. 

Can you help me please?

Thanks

Niall :-)