What about it? You told the SD class that pin 4 was it's pin to own. Don't touch it.
Ok. I set pin 10 as you told me, don't touch anymore to pin 4, so what do I write in SD.begin()? I tried with nothing written in it but still doesn't work.
Which half?
It depends on what I write. It can work for 10 min without any problem but, if I add two lines, the card becomes a ghost, impossible to detect it. (I perfectly know what you'll say). The thing is I tested the sorting programme before and when I mix the two, it fails.