Automate Logon grayed out

[Billieray]

Maybe it's a noob question, but I was trying to change the properties of a session and in particular to check the 'Automate Logon' box to set up a session through a jumphost.
The box is gray and I can't modify it. I checked the behaviour for all other sessions and found out the same.
Even if I create a new session the box is grayed out.
I can't see anything that conflicts with that option, can anyone help me out?