Can you display the name of the person that uploaded the file onto the page? Whatever code does that could be used to set the file name in the server behavior. You would have to append the "file extension" value from the bindings at the end, which you could get from the bindings and then copy and paste the same value you use to display the name on the screen to use as the file name.
Get it showing on the page first to make sure you have the correct value. If it comes from a recordset, then make sure the recordset is above the file upload code.
