The library does not work with AOL (Google and Yahoo are OK). AOL uses openid version 1.0 and I think it is due to this. I have tried extremeswank - works with AOL - no problems, and sreg works with AOL too.
I am using the latiest version 3.2.0.9177 of dotnetopenid.
You may check code and configuration at 'http://stackoverflow.com/questions/1311607/sreg-yahoo-problems'
May you please check support for version OpenID 1.0 ?
Thank you Bye
Vitaly