why cannot connect to libvirtd using virsh ???

[tommy]

[root@test2 ~]# virsh -c quem+ssh://root@192.168.10.175/system

root@192.168.10.175's <mailto:root@192.168.10.175's>  password:

error: failed to connect to the hypervisor

error: no connection driver available for quem:///system

 

But, on the same terminal using virt-manager to connect to 192.168.10.175 is
successful.

 

Why ?