Hey I had the very same issue with my DIY ekit and the trigger IO. I thought I had wired the piezos wrong. So I took the ekit pieces to the local music shop.
I decided (after trying it with a roland drum brain) to sell the trigger IO and purchase the Roland TCM 6. Sorry this wasn’t more helpful. There are a few Trigger IO users on the forum who seem to have had success with
setting up the unit to trigger properly. Good luck and happy music making.

Myron