VPN & only possible to ping 5 of 10 servers.

Hello i have a vpn connection with my isa server and i can access my lan.
The problem is i can only ping only half of my servers on my lan, the other
half not.

It seems that the servers with special services (dhcp server, dns server,
exchange server, domain servers) reply on pinging, the others not. Dns is
working because we can ping to the servername (from the servers who reply
anyway).

Are there services that are needed for pinging to work ?? Or is there
another explanation??

Many Thx.

Ok, solved the problem myself.

The default gateways were not set