in the upload file behavior, you have bond the File Name setting to the server file name variable.
This is circular logic:
The Server file Name variable is created by the Upload behavior. Is the name of the file that the upload behavior creates in the upload directory based on the File Name setting you pass in, and any renaming that may happen based on your settings for if the file already exists.
the default setting for the File Name is:
use that instead of trying to bind it to the server file name variable.