The GUI has not yet been updated to fully reflect Kad. One consequence of this is that starting Kad is a little strange. Kad is started if you let aMule auto-connect on startup or if you click the Connect button on the toolbar to connect. If, on the other hand, you select a server and manually connect to it (double-click it, or right-click and choose Connect from the context menu), then only the ed2k network is started and Kad is not.