If you are using an android phone and having a difficult time getting a scan to register, try the following:
Make sure your NFC is turned on under your phone settings.
Make sure you are bringing the area of your phone where the NFC is located to the sensor and holding the phone there, be careful not to wave the phone around the sensor but instead hold it still.
Try scanning without opening the Scan dialog. On Android, if you just open the dashboard view, you should be able to touch your phone (wherever the NFC is located) to the sensor and it should scan automatically. Please wait two seconds after you feel the vibration before moving the phone.