Not Registered on Network topic

we write original imei with box. phone is ok. working. if i install original stock firmware or custom, phone said to me "not registered on the network." when try to make call. and we write original imei with box. phone fix again. but i cant install firmware

Phone i9500
Rom: Stock 4.3
*#0011# IMEI CERTI FAIL


How can i fix it? Anybody idea?