Cannot dial ADSL via PPPOE

[acel]

I installed the latest raspbian on raspberry B+, and also installed ppp, pppoe, pppoeconf. Then I set up PPPOE via pppoeconf, and start PPPOE by sudo pon dsl-provider, but raspberry always complains the below message. I tried add the current user (pi) to dip group (I checked /etc/group and it seemed succeeded), logout, reboot, but none of these can fix the below error and make pon executable. Has someone else got this issue before? How can I make it work?

pi@raspberrypi ~ $ sudo pon
Error: only members of the 'dip' group can use this command.
pi@raspberrypi ~ $ pon
Error: only members of the 'dip' group can use this command.

[topguy]

Type "groups" , this will list all the groups the currect user belong to. Then you should be sure that the user is properly added to the "dip" group.

[acel]

Type "groups" , this will list all the groups the currect user belong to. Then you should be sure that the user is properly added to the "dip" group.

Thanks. Yep, I also tried this, groups shows both pi and root are member of "dip".

[JPelletier]

I have the same issue, I'm root and I can't use pon! I always get the error:

Error: only members of the 'dip' group can use this command.