AutoUpdate don't start automatically when connected in LAN

Hi,
I work in a Local Area Network, and i use avast home 4.5.
The autoupdate don’t start automatically, but i must activate it manually, because probably it don’t find that i’m connected.

If a work with dial-up connection, it work fine.

In Lan i leave the options

  1. i connect to internet using dial-up
  2. computer is costantly connected

NOT checked
because aren’t true.

But if i active “2. computer is costantly connected” avast open the panel for making a dial-up connection, but i’m already on-line via LAN!

Can you help me?
I’m Italian, excuse me for errors…