Pppoe Airport Settings


I have just swapped my USB modem (which works just fine) for an Ethernet one connected to my new Airport Extreme basestation. As far as I can tell I have put in all the settings required, my Network Status tells me I am part of the correct Airport Network and that I am connected to the Internet, but the Airport icon in the menu board just sits there looking for the PPPoE host and won't connect. My ISP (not very Mac orientated) tells me I should be using PPPoA, can anyone advise me further ?
Help !