Hi to all and thanks for your help.
The answer is for all of You.... just quoted the first.
Hi Masteripper, I've checked the card, a Kingston 8GB class 10, formatted with SDFormatter with all options, checked it with H2testw, wrote image with Etcher. Put it in the BX2, powered on, only purple led after an hour.... nothing else... I followed the suggests of TKAISER and TIDO too, looking if something gone wrong but everytime the same results. I'm a little bit tired...