Make sure the ReadySet is properly connected to the solar panel (see pages 8-15 of the user manual).
Press the button to begin charging. If it still does not begin to charge, make sure the solar panel is placed in direct sunlight. If the sun is low or the day is cloudy, there may not be enough sunlight to charge the ReadySet. If so, you will need to wait for a sunny day. If it still does not charge during a sunny day, try using the Grid/Mains charger.