Unable to connect usb intuos wacom pen and touch tablet

Code:

herve@grosse-machine:~$ uname -a
Linux grosse-machine 3.13.0-91-generic #138-Ubuntu SMP Fri Jun 24 15:58:13 UTC 2016 i686 i686 i686 GNU/Linux

Code:

herve@grosse-machine:~$ lsusb
Bus 002 Device 003: ID 093a:2510 Pixart Imaging, Inc. Optical Mouse
Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 004: ID 056a:033c Wacom Co., Ltd
Bus 001 Device 003: ID 1210:25f4 DigiTech
Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Code:

herve@grosse-machine:~$ xsetwacom --list devices
(no result)