OK, I got my connection problem fixed.
First I can not use the ip address assigned to me, through 1723 port on this ip is open, but I simply can not connect through it, I need to use the shared ip instead, but now I can connect through it. Thank you very much. :wink: :wink:
A note for those who using Windows from xp to 8:
Select pptp protocol.
Select request encryption.
Use MS-CHAP v2.
I am able to connect to vpn service by using an android ICS phone too, but only through the server address, not through the assigned ip address.
Btw, To check if port 1723 is opening, type the following in CMD widow:
telnet <insert ip here> 1723.
If it is not opened, it will shown a connection refused messages.