That’s good, this confirms that there is most likely something wrong with your piezo disc. I’m assuming that the disc is shielded, is this correct?
Please make sure that the shielding is not connected to any part of the brass or ceramic part of the disc. Also, it’s important to make sure that the PZ1 and PZ2 wires are making proper contact with the 2 parts on the disc. When you measure the resistance between the red and white wires, the reading on your meter should continue to rise until it is too high to measure. This should let you know if the red and white wires are connected properly to the disc.