Typically this is a result of the IIS log properties not being set correctly. You need to log into your server via remote desktop and pull up the IIS administration console.
Right click on the IIS web you are having an issue with and select properties then click on the properties button under the logging options.
Now click on the advanced tab and check the box for the referral information.
Once this option is set all future logs should contain referral information. However, any logs taken prior to this point will not have recorded it and it is not possible to recover that information since it was not recorded.