I have an Ipad 2 16gb, I bought a sim card yet it says sim card not installed

Hi Peeps, please can someone help in what I do next! the ipad 2 will find the sim card network for about 15 secs then goes off and says sim card not installed.

does anyone know whether I need to update or download certain software for this to work.

It is the IPAD 2 16gb, sim card checked with network provider and its working fine!!