[one-users] Missing "VNC" icon in sunstone

[Gianfilippo]

Hi all,
I have performed an upgrade of opennebula using RPM packages on centos 
6.4, from 4.0.1 to 4.2.0.
After the upgrade, the VNC icon in the sunstone page is not appearing 
anymore on any running instance. VNC proxy is running and no errors are 
shown in sunstone.log or novnc.log.
Direct VNC connection to instances is working correctly.
Any hint?

Thanks for your help.