Dear customer,

Could you please check if the sensor under your account is set as a standalone sensor? If so, to move the stand alone sensors to a zone, first you have to go to Settings->Sensors->Edit(upper right corner) and then delete the sensor. Next you will have to go to the home page. There is a drop down menu and please select your Sprite controller, then tap the "+" button on the upper right corner,  go to Add a Product-> Plant sensor and then select the zone and complete the following procedures to add the sensor. You will need to press the button 6 times on the back of the sensor to change its mode to Setup mode (light blinking slowly).

If you have any further concerns or questions, please do not hesitate to reach out to us. 
 
Regards, 
Netro Support