Arduino M0 bootloader issue

Hello Everybody,
i am working with ATSAMD21G18A breakout board. i have uploaded a SAM-BA bootloader through Atmel Studio using Atmel ice but i am not getting USB detected getting message as "USB DEVICE NOT RECOGNIZED"

i have also uploaded the code through c++ compiler in Atmel Studio and the board is working fine but the arduino program uploaded through atmel studio not working. i have uploaded a simple led blinking program.

need urgent help.....