[libvirt-users] error libvirt

I have a problem con libvirt, if running this python code: import libvirt conn = libvirt.open("vbox:///session") return this error: libvir: QEMU error : server closed connection libvir: warning : Failed to find the interface: Is the daemon running ? libvir: Remote error : unable to connect to '/var/run/libvirt/libvirt-sock': Connection refused libvir: warning : Failed to find a node driver: Is the libvirtd daemon running ? libvir: Remote error : unable to connect to '/var/run/libvirt/libvirt-sock': Connection refused libvir: warning : Failed to find a secret storage driver: Is the daemon running ? If I running the python code in sudo mode, I don't have error. I have before add the my user at the group "libvirtd" with: sudo adduser user libvirtd Angelo