button 2 (middle mouse) wacom pen not working for sculpting

I have a wacom bamboo tablet for sculpting. I know it is a small tablet.
Works perfect only I cannot rotate in sculpting by using button 2 wacom pen (middle mouse).
Button 2 is working perfect in edit and object why not while sculpting?

Blender 2.68 OS Linux (opensuse 12.3 x86_64)