If you have the correct level of access to the server you can tell it to interpret files with .xml extension as .php...
I'm not sure if that solves your problem
To me, it sounds like your problem is that you're not making the XML file correctly.
Have the .php file write an XML file and display it with the .php extension, then copy that into an XML file and run that file as .xml and see if it works like that.
If it does then your diagnosis on the problem is correct...but to me it sounds like you're missing the "<" like it says
I'm not sure if that solves your problem
To me, it sounds like your problem is that you're not making the XML file correctly.
Have the .php file write an XML file and display it with the .php extension, then copy that into an XML file and run that file as .xml and see if it works like that.
If it does then your diagnosis on the problem is correct...but to me it sounds like you're missing the "<" like it says
