yes pretty sure! but I found the problem!
I installed dom0 as amd64 and one domU as i386 and a other also as amd64!
The one I was trying to set up was installed as i386 ( don't ask why ... I don't know, probably the heat in the office )
As I noticed this I tried it on the amd64 installation and there it works ! so I gues my problem is fixed
thanks anyway for the help