D2 Delta and Flight Stream 510 Connext

Following user manual procedure of pairing D2 Delta with Flight Stram 510 Connext device (installed in GTN 650) results in failure. Nothing happens after entering bluetooth pairing mode on Connext device GTN 650 and holding D2 MENU > Settings > Aviation > Connext > Pair Connext > Status > Waiting for Device.
Anybody has any idea? Thank you.