PPTP VPN for Separate SSID

Hi
I have a rb751u-2HND with its very default configuration. the comes with By Default.

on LAN 1 i have the WAN interface for coming from modem assigned by DHCP and i am using the default MIkroTIK SSID.

Now i created a Vitual AP and created the the pprp client and using string vpn Guide

http://www.strongvpn.com/setup_mikrotik_pptp.shtml

created the pptp client and forward the incoming and outgoing interface to virtual AP.

Now the problem is the Virual AP is not assigning the IP addresses even i have added the IP addresses in the “IP Addresses” field and assign the interface to Vitual AP . but still its not assigning ip addresses . if i enter manual IP address in my windows machine then it works.

Can any one point me out where i am making mistake.

Thanks