error 800

Hi guys,When i connect to vpn server i faced a problem "error 800" on windows 7.
I did the following steps to repair this error on my windows server 2008 machine:
1-I setup Routing And Remote Access server for vpn
2-I opened port 1723 "Tcp" And port 500,4500 "UDP" on Firewall on my server
3-I opened the last port on my Router

but I still receive The same error please help me !

Thanks guys