Hey I have this configuration in my web.config
I've had experiences where logging systems fail silently without raising exceptions. I suppose this makes sense because if the logger is logging errors then how can it log an error that it's unable to perform logging?
So if the file isn't created on disk, start by looking into file system permissions to ensure the user your application is running under can write a new file to that disk location.
For testing purposes you might want to manually create the file on disk that should be written to and open up permissions for everybody to write to it. If the logger starts writing to it then you know it's permission based rather than configuration based.