Hi,
You're using Virtual Private Network ? You probably didn't set gateway property or you didn't enable Incoming VPN Connections . Try doing it one more, you can follow and learn whole process on link bellow :
http://www.sevenforums.com/tutorials/4517-virtual-private-network-vpn-enable-incoming-vpn-connections.html
One more interesting link :
http://www.pcworld.com/article/210562/how_to_set_up_vpn_in_windows_7.html
Regards