[libvirt-users] connect libvirt and virtualbox

conn = libvirt.open("vbox:///session") return this error: libvir: VBOX error : internal error unable to initialize VirtualBox driver API Traceback (most recent call last): File "prova.py", line 5, in <module> conn = libvirt.open("vbox:///session") File "/usr/lib/python2.6/dist-packages/libvirt.py", line 163, in open if ret is None:raise libvirtError('virConnectOpen() failed') libvirt.libvirtError: internal error unable to initialize VirtualBox driver API why?