VPDN is typically used when your client device connects to an access server. What is your setup ? Are you simply trying to connect to an ISP using PPPoE ? And what is your client device/platform (e.g. Cisco 887) ?
thanks , appreciate if you can send the config as well , also what the difference between VPDN and dialer interfaces , when should we use each? is it device specific ?
dialer interfaces are for routers, I don't even think you can configure those on a ASA. Either way, the link below has sample configs for the ASA as a PPPoE client (since I don't know which OS version you are running: