Why PPPoE Connection fails with error 691 - ADSL2+ Modem

Question

On Windows 7, an ADSL2+ modem is used to connect to my ISP using a PPPoE connection.

1-Username and password are correct.

2-The modem is configured to accept bridge connection with my ISP VPI VCI ports.

When trying to connect with PPPoE, the authentication fails with an error 691

How to know the real reason that lets the authentication fails ?

Answer 1

Finally i figured it out;

windows logs the PPPoE connections to a file in c:\windows\tracing\PPP.log

When taking a deep look at this file it shows the reason Account disabled so it's ISP related.

But why the message is not displayed to the windows users ?