Bridging 2 Vera Edges

Hi all,

i have had a vera edge for a while now in my workshop and now want to start to automate the house. I have purchased another edge and got them both on the latest firmware. I have attempted to set them in bridge mode using the add device ->upnp device route but it never detect the other vera box.
Is there something fundamentally stupid i am doing or does this just not work?

thanks

Aaron