GSM/GPRS/GPS Tracker ,no location details

Hi All , purchased a TK102 GSM/GPRS/GPS tracker recently. It uses SMS txt messages to provide information regarding location of device i.e you ring sims sims card(TESCO) in Tracker , hang up, and it should respond with Longitude and Latitude position of tracker(TK102). Device does respond with a txt message but without any location details Lat and Long details are blank. AS i mentioned i use a 3g Tesco SIMS card in TK102 device and was wondering does anything need to be set in order for SIMS card /TEsco network settings, to collect location details and forward in txt message.

Regards, Jumper

I'm not an expert, but I think some of these services dont work on Irish networks. But I might be wrong.

Is it outdoors? Is the signal indicator flashing to show it has acquired satellite lock?