My ddj-rb won't play any loaded tracks on rekordbox box 5.0

I'm new to DJing but I'm so keen to get into it, however after loading up a track to either player on the software, the play buttons on the decks don't light up green, like they should and also I can't play any tracks.

Any advice would be greatly appreciated, looking to start DJing as a new hobby and hopefully DJ professionally one day.
Thanks in advance