A : 1. Battery is low. Charge the unit with 12V external power for at least half an hour; 2. Make sure the unit is already connected to GSM network (Green LED flashes 0.1 second on and 2.9 seconds off). If not, please first refer to above question – Green LED stays 1 second on and 2 seconds off (can’t get GSM signal) after the unit is turned on. 3. GPRS tracking settings is not correctly set. For example, if set via SMS command, the format is: 0000,A21,1, 18.104.22.168,8056,CMNET,, In this comm.