Unhappy Mobile Operator not found on Nokia Lumia 920...

Hi, I am a new user of windows phone. A few days ago a relative give me his used Nokia Lumia 920 in critical condition. It was not booting, then I studied a lot & flashed an Amber rom. But the problem is my desired operator (Banglalink) is not working on it. There are five GSM operators in our country (Bangladesh). I checked four of them, only two works (Grameenphone & Airtel) but other two don't (Banglalink & Robi). I tried several roms but same problem found. Also selected operator in manual search, but the problem still remains. I really want to use the phone & somebody please help me to solve this problem.I attached my recent Amber rom detail & operator name while found in manual search.