Interface dslite-wan_6_4 doesnt come up

I have to use dslite at my FTTH. The specs are:
pppoe for authentification.
So I installed the dslite software. After configuring "wan" with protocol pppoe and "wan6" with protocol dhcpv6 it seems to work.
the virtual interfaces WAN_6 and WAN_6_4 spawn. I get an IPV6 address but no IPV4.
All around I read that dslite starts up automatic and gets the AFTR address direct via dhcpv6...
But it dosnt work...
Anybody here with a similar constellation?