Configure your Ubuntu box as a IPv6 router

[sonbolHol]

hi every body,
i will explain to you my situation

my OS is ubuntu 14.04

i use a 3g modem which give me just a dynamic ipv4 his interface is ppp0

i create successfully a tunnel with he and i can ping ipv6.google.com

i modify     /etc/sysctl.conf

Uncomment the line which contains net.ipv6.conf.default.forwarding=1

now after install radvd and configure it  in /etc/radvd.conf

interface wlan0
{
   AdvSendAdvert on;
   prefix 2001:470:1f13:40c::/64
   {
        AdvOnLink on;
        AdvAutonomous on;
   };
};

i use the wlan0 interface because i want to give a ipv6 adresses using a WIFI automatically
then i restart it sudo /etc/init.d/radvd restart

but when i create a wifi with my laptop in the clients side i just see a ipv4 adresses and no ipv6

i use this https://wiki.ubuntu.com/IPv6?action=show&redirect=IPV6#Configure_your_Ubuntu_box_as_a_IPv6_router

so i hope some one help me

i ask am i supposed to configure the wlan0 in /etc/network/interfaces
or is that works just for the eth0 interface