Ipad4 facetime and imessage not activating

i have an ipad4 Wifi.i recently restored my ipad via itunes back to original settings.now it has ios8.2. But now facetime and imessage does not work anymore. It keeps saying facetime and imessage cannot be activated.everything else is working fine. even the wifi is also working very well. i tried everything possible from changing the DNS to restoring ios but still it does not work. i think it cant be a hardware issue beacause wifi works well. so i think its something else. please help me!!