Are you sure you made the correct changes to the log4net.config file as well as adding the needed setting in user.config as indicated in the article?
Note that changes to user.config are not automatically detected so you have to touch web.config after editing user.config.
Then of course errors will only be logged when errors happen but you should see at least some info logging for application start event after touching web.config
I think you misunderstand the customerrors element in Web.config
RemoteIOnly means it will show the friendly error page for remote requests and only show the error details when browsing locally ie using localhost as the url. To make it always show the error detail you need to set it mode="Off"
Hope that helps,
Joe