sim card problem after flashing,w910i

hi,i have a problem on my w910i, i flashed it with ne firmware,but now after some time he shows me insert sim card, than i turn off phone and turn on,everithing ok,after some time he again shows me insert sim card,before flash no problem like this,i would really apreciate help thx sorry for bad writing my english is not very well.

Remove sim and clean contacts on it and also sim contacts in the phone,try to insert some other sim card to check is it same.