Hello. I changed a sim card from S3 mini to a S4 mini and the problem was that S4 mini couldn't find the network for the sim card so I put back the first sim which was in the S4 mini and was working and now it won't detect it, it says "No sim card" then I switched the sim from s4 mini that couldn't detect it to s3 mini and it's working. I have no idea what to do now. Many thanks if you can help me.