Hi Alessio,
Can you please provide me with the folllowing information:
Is the dock connected directly to the laptop? Or via an external hub?
Did you perform a clean install of the developer preview or was it an upgrade?
Can you try disconnecting the dock, uninstalling the DisplayLink software and then run the cleaner tool (
http://displaylink.com/support/ticket.php?id=297) before reinstalling and then reconnecting the dock?
Please see
http://www.displaylink.org/forum/showthread.php?t=896 for some other suggestions for things to try when your device doesn't come up.
If this doesn't help let me know.
Thanks,
James