nm-vpn over ppp?

["zuse gmx at" <zuse gmx at>]

hi!

i use debian 4 with 2.6.28 and nm-applet 0.6.6.

i have a problem in using network-manager-vpn with my (in case of not at 
home) gsm-connection.
i establish it with gnome-ppp which works fine.

after it a ppp0 device appears. all internet over gsm is fine (mail, 
browser, ping, ...) and my eth0 is down (no wonder).
put i can not establish a vpn connection if in gsm-mode. all configures 
vpn-peers are deactivated in nm-applet. if have lan or wlan they are ok.

what can i do? i think the nm doesnt check my ppp or?

best regards
chris