OK, maybe the reason is simple - the address is not correct so it cannot find your device, can you check http://www.espruino.com/Reference#l_NRF_connect and see the hint about addresses on the bottom about static random etc. It would be best if you would first scan for your device and see how the address is reported and use exactly that string.
EDIT: but since you actually get connection and then get disconnected this makes no sense
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
OK, maybe the reason is simple - the address is not correct so it cannot find your device, can you check http://www.espruino.com/Reference#l_NRF_connect and see the hint about addresses on the bottom about static random etc. It would be best if you would first scan for your device and see how the address is reported and use exactly that string.
EDIT: but since you actually get connection and then get disconnected this makes no sense