Cisco Small Business Router Error

Hi, I'm trying to configure the above , but keep getting the following message when testing the connection:

no configured DNS server(s) are routable through the selected interface

This occurs at the 'Exit Interface' test. Thing is, I can't find any mention of the exit interface, nor find anywhere that matches the suggested solution.

EDIT: The suggested solution is:

'Select 'Enter IP address or hostname' option or add a 'host specific/network specific/default' route through this interface and retest connection'

Anyone out there set one of these up before?

Help!

so it wants you to route traffic from the LAN interface to the dsl one.
you also might want to let the router know what your ISP dns servers are ?

I've already let it know what the ISP DNS servers are, but that didn't help...