Pulse Sensor Amped giving wild reading

Hi there

I’m desperately trying to understand why my Pulse Sensor doesn’t seem working properly.

It most of the time doesn’t do any reading
When it does, the reading fluctuates between 20 and 200+ without me moving my finger
It also sometimes give me reading when nothing touches the reading.

This happen when I try the simple example program avaible in the PulseSensor Playground Librery

My questions is: could it be dysfonctioning or am I missing a key information on how to use it?

Thanks for your help

Jeanne