DHCP working but clients don't have internet

DHCP working but clients don't have internet

just like the tittle says. MY DHCP assigns IP's and all that stuff to clients, however client's don't have acces to the internet. Here's my DHCP configuration:
ddns-update-style none;
option domain-name "home.lan";
option domain-name-servers 8.8.8.8, 8.8.4.4;
default-lease-time 600;
max-lease-time 7200;
option broadcast-address 10.8.8.255;
subnet 10.8.8.0 netmask 255.255.255.0 {
 range 10.8.8.5 10.8.8.9;
 option routers 10.8.8.1;
}
broadcast-address 10.8.8.255
I have of course added INTERFACES="eth0" in /etc/default/isc-dhcp-server and added eth0 interface definition into /etc/network/interfaces
auto eth0
iface eth0 inet static
address 10.8.8.1
netmask 255.255.255.0
gateway 10.8.8.1
broadcast 10.8.8.255
I've added net.ipv4.ip_forward=1 in /etc/sysctl.conf
On the net, I've read that it is possible to simply share the net using linux GUI. (here's easy guide with screenshots on how to share the connection) But it doesn't work in my case. If I change on my wlan0 (auto DHCP) to (share to other computers) I don't have internet access after rebooting because wlan0 do not automatically get connection info.
Clients receive IP, default gateway, DNS'es, netmask and so. Mind any of u helping me with finding out, why it is not working? Im using ubuntu 12.04. Thanks.