Cable modem connection and MS PPTP

We are attempting to provide several of our remote cable modem workers with secure internet access to our LAN. We have a Windows NT 4.0 RAS(PPTP) server as the VPN gateway and MS PPTP installed on the clients.
The problem I am having is that when the cable modem users connect the login script on the RAS server isn’t running to map the users network drives. When we do a regular dial up, however, it works. Can anyone give me some insight on this?