I don't see any bubbles in the bubble counter after solenoid is switched ON

If you don't see any bubbles in the bubble counter once your solenoid is energised please follow below steps to investigate your issue :

1) Make sure the needle valve is open by turning it anticlockwise at least half-full-turn.
2) Switch your solenoid ON/OFF and check if you hear clicking noise inside the solenoid. If you don't hear a clicking sound, please contact our support team.
3) If you hear clicking noise, but no bubbles in the bubble counter, power up your solenoid and remove the tubing from the bubble counter
4) if the tubing is removed and you still don't see any bubbles, remove your bubble counter
5) without bubble counter, open needle valve fully and switch your solenoid OFF/ON again, making sure is ON and you heard clicking noise inside. 
6) at this point you should hear a hissing noise from the needle valve
7) if there is no hissing noise from the needle valve contact our support as we may need to perform a few more steps or just arrange needle valve cleaning repair for you.

Answers :
1) If you get bubbles after removing the tubing, please make sure your diffuser is clean or not clogged. If you have an additional check valve, please remove it to see if the check valve is not blocking the flow
2) If you hear hissing noise after removing your bubble counter, check valve in your bubble counter is blocked. Contact our support team if this bubble counter was purchased from us.