Getting constant GSR output no matter what


I was working with the GSR sensor from Seeed studio. However, I get constant readings from the sensor. I have tried to stimulate the finger by pinching it very hard, watching a very funny video etc. The sensor output just doesn’t change. I have connected the output of the sensor to an arduino nano and have let the TP4 pin of the sensor unconnected. Can somebody suggest on how to proceed?