Connecting to NT4 server using VPN

Hi,

I have created a VPN using a Watchguard firewall. I am
able to connect to shares on an NT4 server using XP Home
and Pro. I have been unable to do so using 98SE. I am
able to ping the server from the 98 system, but when I
attempt to connect to a share using the format

\\server_ip_address\share_name

I get an error stating

"Windows cannot find '\\server_ip_address\share_name'.
Check the spelling and try again, or try searching
for the item by clicking the Start button and then
clicking Search."

Does anyone have any ideas on where to go with this?

Thanks,

Dwaine