setting up dialup in Mandrake 7.1 kppp

I’ve tried to set this up several times.. even RTFM and online help.. gets as far as dialing out, checking login & password, then just disconnects. The correct modem is configured, phone number and account info is correct.. what am I missing here? Any suggestions appreciated *g* .. I have a 3-way boot (win98/win2k/mandrake 7.1) but feeling like an absolute “newbie” in Linux..