I cannot start the sequencers

Hello,
I recently got my new key step pro, and I can’t start the sequencer (the arp works fine). After I have entered all the notes of the sequence, when I tap into the reset (play) button, only the first slot lights up white, and nothing really happens. What should I do?
Thanks,
Arnau

Make sure the clock setting DIP switch on the rear is set to Internal.