I got trouble with SAMD21 xplained pro board.
While it's shown in Device Manager correctly after successful program compilation it fails to load a program (screenshot is here https://yadi.sk/i/bFTv_UGEhUm8h).
I have tried to use both Atmel Studio 6.2 and IAR. First one give me message "failed to launch program. Error: the Service threw anunknown exception".