compile and download to flash

Hi,
I have a espruino rev 1.3b board and I'm using linux throuth virtual box.
I compiled the project, download, reset , in windows device manager, it is recognised as an unknown device, but I download the official one from espruino, it works fine, a com port.
I tried these command:

 ESPRUINO_1V3=1 RELEASE=1 make serialflash
sudo python scripts/stm32loader.py  -ew -k -p /dev/ttyACM0  ../espruino_1v81.581_espruino_1r3.bin  // this is the official bin file, it works.

anybody can help me?

Thanks,
Anthony