Troubleshooting Piezoelectric element

Hi guys,
Im working on a project where i want to detect vibrations on a surface with a piezoelectric element attached on that surface.
Further down the road I want to be able to detect the distance between the source of the vibration and the piezo element based on the strength of the vibration.
I followed the knock example from the arduino library but the only thing I managed to achieve is to register a response only if I'm pressing the piezo but it returns 0 if I knock next to the piezo. Can t be that the piezo I'm using is not sensitive enough, or any ideas what I might be doing wrong?

Thanks alot

Could your resistor be too low? Could you have the disk backward? Are you sure it's a raw disk and not a buzzer with active electronics?

Could it also be that the output is too low or that the disc is damaged... You might need some amplification to make it work as you expect. Distance measurements based on that method would need to be calibrated first and would require a specific impulse level (Knock) or a "Louder" knock might appear to have a different difference especially on metallic surfaces.

Bob