NAV 2013 Active Session

I am trying to use the Active Session table from C/AL Code in NAV 2013.
I am doing the following:


ActiveSession.SETRANGE("Session ID", SESSIONID);
ActiveSession.FINDFIRST;
ServerName :=ActiveSession."Client Computer Name";

However, when that code is executed I get the following error:
"There is no Active Session within the filter. Filters: Session ID: 1"

If I look in SQL at the Active Session table, there aren't any entries. I have restarted the NAV Service multiple times.
Any ideas?