PowerConnect 8024F Q-in-Q

Hello

We have two Power Connect 8024F switches with a 10G Metro E uplink between them. Both ports are trunk ports with a single vlan between the two devices from the provider. They are Te1/0/1 on both switches

I have an interface on each switch that I would like to plug into the core network in both locations as a trunk port, tunneling 20-30 VLANs over the one VLAN.

So far, I have set both customer interfaces to switchport mode general, switchport general pvid 100

When setting mode dvlan-tunnel on te1/0/24 I lose access to the device, it stops pinging and telnet session dies.

Is there anyone around with experience in getting Q in Q working between two 8024F?

Cheers

Nick