Authentication error when launching virtual manager

Launching virtual manager as non root users gives authentication error.

check user if part of libvirt group if not add user to group

csr@MainPC:/etc/modprobe.d$ groups csr
csr : csr cdrom floppy sudo audio dip video plugdev users netdev bluetooth lpadmin scanner
csr@MainPC:/etc/modprobe.d$ sudo usermod -a -G libvirt csr
csr@MainPC:/etc/modprobe.d$ groups csr
csr : csr cdrom floppy sudo audio dip video plugdev users netdev bluetooth lpadmin scanner libvirt
csr@MainPC:/etc/modprobe.d$ cd
csr@MainPC:~$ 

launch virtual manager