Here's the URL to determine if a machine is within your IP 
authentication range: http://safari.bvdep.com/bo/ShowIP.asp

Example of not being within an IP range:
IP: 209.204.147.42
Normalized IP: 209204147042
User ID(s) found:0

Within the IP range:
IP: 209.204.147.42
Normalized IP: 209204147042
User ID(s) found:1
User Id 853 between IP1=209204147001 and IP2=209204147042

If you find a machine is not being automatically logged in, use this URL and return all information contained to us. 

If you find that a machine is not logged in but within the IP range, it's possible that a previous user used the logout button. Tryclosing all browser windows, opening a new browser session, and going back to Safari.