UT on XEN - network traffic not displaying

[speciall]

Hello,
After a few try's I managed to get UT working in bridge mode on my Xen server

Config:

Internet --- DSL linksys router --- Network 0 --- Network 1 ---- Internal network

Network 0 : Wen interface of UT
Network 1 is the Lan interface where the rest of the VM's and network is connected to.

It all seems to work, but there is one strage thing , in the dashboard I don't see network traffic. Always 0KB/s

I tested with changing the ext and int interface and then it displays the traffic reverse (When I'm downloading something is see this value in TX)

anyone an idea?