This is actually a very common issue and easily fixed. The PSI gauge will not move until you have reached around 7-8 PSI and we recommend inflating to 15 PSI.
Surprisingly the board can feel hard and fully inflated when still under 7 PSI. There is no concern of over inflating the board with the hand pump, as the pump can only go to 15-18 PSI and the board itself can handle a much higher PSI. We only recommend 15 PSI for liability reasons, but we assure you there is no way to manually over inflate the board with a hand pump.
Please continue to pump the board until the PSI gauge begins to register. If you can no longer pump the board and the PSI gauge has not moved, please remove the pump hose from the board and then re-attach it, this will 'jump start' the needle as it could initially be a little stuck.
If you are still having issues with the gauge, please email us at firstname.lastname@example.org and we can help troubleshoot further!