says no sim card but calls work

[pratyaksh tyagi]

i have a galalxy grand gt-i9082. i updated it to cm 12.1 and its now android 5.1. when i lock the screen the line comes in "NO SIM CARD DETECTED-NO SERVICE". the calls works fine!! IMEI is also available.
my cyanogenmod ver- cm12.1-20150405-i9082
any suggestions getting out of this?