Proxmox 3.1 - Can't add node to existing cluster

Hi,
I just try to add new node to existing cluster (both 3.1 up-to date) and I got the next error message:
root@server202:~# pvecm add 192.168.10.121 -force
I/O warning : failed to load external entity "/etc/pve/cluster.conf"
ccs_tool: Error: unable to parse requested configuration file

command 'ccs_tool lsnode -c /etc/pve/cluster.conf' failed: exit code 1
unable to add node: command failed (ssh 192.168.10.121 -o BatchMode=yes pvecm addnode server01 --force 1)

any Idea?

Best Regards,
Star Network.