To get a desktop enable for remote access you could use the command line to ensure that regarding which of you user have access on the PC you are able to help out in trivial task.

To do so you could run this line as root:

gconftool-2 –direct \
–config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
–type bool \
–set /desktop/gnome/remote_access/enabled true

 

Sometimes the machines is unattended, so if no user is around to give you access then you will not be able to get that session. To disable the prompt message just type:

 gconftool-2 –direct \
–config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
–type bool \
–set /desktop/gnome/remote_access/prompt_enabled false

This is up to the admin, this could just hide that you access that session, just be careful. This settings has privacy issues.

gconftool-2 –direct \
–config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
–type string \
–set /desktop/gnome/remote_access/icon_visibility never