No service!!! On kk modems.

i need help this problem has been there with me since i bought my opo 2 months back. i received it with cm11s build which was not official. so i had to manually upgrade my opo to cm12s after that i have flashed many lp roms even cm12.1s but never a kk rom. then i felt like going back to kk i flashed @Bobbi lim cm11s mod rom 3.5 and i got no service tried many things still no service i then flashed cm11s 44s factory image but still got no service. then i gave up and continued to stay on lp roms. then till recently i found that it was not the roms but the modem if i flashed lp modem on kk roms i got service but with black screen bug but when i flashed back kk modem again no service.
please help me is there something wrong with my opo hardware. @Heisenberg @Vivek_Neel and anyone else who has solution to this problem.
sorry for making it so long.