rc3.d

[Default Debian Reader <debianuser@jkeating.static.execpc.com>]

I want ppp to start at boot time so I made a script that does has the 
following lines
#!/bin/sh
pon MY_ISP
i saved this file to /etc/init.d/pppstuff*
then in /etc/rc3.d/ i did ln -s /etc/init.d/pppstuff /etc/rc3.d/S20pppon
this doesn't start my ppp connection at boot..why not?  
can anyone help me with this please?