if the session binding does not get created automatically, you may need to create it manually.
on the bindings panel, click the plus button, select Session and enter the name for the session binding.
sometimes the sites _notes folder can become corrupted and cause creating new bindings to fail.
use the OS File System explorer to browse to the site and delete the _notes folder if you are not able to manually create the binding.
can you send a copy of the userconfirm.php file so i can see how it is set up.