You might also want to check what rights you have against that interface, you might be able to see it but not write to it.
pi@raspberrypi:~ $ ls /dev
autofs cuse i2c-1 loop5 mmcblk0p2 ram11 ram7 shm tty12 tty21 tty30 tty4 tty49 tty58 ttyAMA0 vcs1 vcsa3 vcsu3 video14
block disk initctl loop6 mqueue ram12 ram8 snd tty13 tty22 tty31 tty40 tty5 tty59 ttyprintk vcs2 vcsa4 vcsu4 video15
bsg dma_heap input loop7 net ram13 ram9 stderr tty14 tty23 tty32 tty41 tty50 tty6 uhid vcs3 vcsa5 vcsu5 video16
btrfs-control fb0 kmsg loop-control null ram14 random stdin tty15 tty24 tty33 tty42 tty51 tty60 uinput vcs4 vcsa6 vcsu6 watchdog
bus fd log mapper ppp ram15 raw stdout tty16 tty25 tty34 tty43 tty52 tty61 urandom vcs5 vcsa7 vcsu7 watchdog0
cachefiles full loop0 media0 ptmx ram2 rfkill tty tty17 tty26 tty35 tty44 tty53 tty62 v4l vcs6 vcsm vhci zero
cdc-wdm0 fuse loop1 media1 pts ram3 sda tty0 tty18 tty27 tty36 tty45 tty54 tty63 vchiq vcs7 vcsm-cma video10
char gpiochip0 loop2 mem ram0 ram4 sda1 tty1 tty19 tty28 tty37 tty46 tty55 tty7 vcio vcsa vcsu video11
console gpiomem loop3 mmcblk0 ram1 ram5 serial0 tty10 tty2 tty29 tty38 tty47 tty56 tty8 vc-mem vcsa1 vcsu1 video12
cpu_dma_latency hwrng loop4 mmcblk0p1 ram10 ram6 sg0 tty11 tty20 tty3 tty39 tty48 tty57 tty9 vcs vcsa2 vcsu2 video13
pi@raspberrypi:~ $ ls -l /dev/cdc-wdm0
crw------- 1 root root 180, 176 Sep 24 16:13 /dev/cdc-wdm0
pi@raspberrypi:~ $ su
Password:
root@raspberrypi:/home/pi# ls -l /dev/cdc-wdm0
crw------- 1 root root 180, 176 Sep 24 16:13 /dev/cdc-wdm0
root@raspberrypi:/home/pi# chmod +777 /dev/cdc-wdm0
root@raspberrypi:/home/pi# ls -l /dev/cdc-wdm0
crwxrwxrwx 1 root root 180, 176 Sep 24 16:13 /dev/cdc-wdm0
root@raspberrypi:/home/pi#
Regards
Matt