v9 Beta does not install on Xen HVM

Hello
I just tried to install the v9.000-8.1 ISO onto my XenServer (as a VM).

Tried it three time and always get an RPM installation failed error at about 96% (will check for details if told how / possible)

Afterwards the installer wants to reboot.
Then the system finds the HDD bootable but does not boot (BIOS says that HDD is bootable and nothing happens after that message)

greetz
chas0rde