pptp vpn connection during installation

[hadian]

i want to install gentoo and my network needs a pptp-vpn connection for connecting to internet.
regarding the gentoo handbook i should adjust the file /etc/ppp/chapsecrets and then use pptp <server ip>.
suppose my username is: 2100
my password is: mypass
server id: 172.16.10.32

i edited the file as:
2100 mypass 172.16.10.32

then i tried to connect by : pptp 172.16.10.32
there is no error message but the connection is not stablished.

what is the correct items for this file regarding my information?
Regards