Badly formed XML, there is no tag

Using glade-3 i got with this error/warning:

[walter@talent Projects]$ gtk-builder-convert uno.xml
Traceback (most recent call last):
File "/usr/bin/gtk-builder-convert", line 772, in
File "/usr/bin/gtk-builder-convert", line 760, in main
File "/usr/bin/gtk-builder-convert", line 161, in parse_file
File "/usr/bin/gtk-builder-convert", line 233, in _parse
assert glade_iface, ("Badly formed XML, there is "
AssertionError: Badly formed XML, there is no tag.

Try saving the file as a libglade project and then try again. It work'd for me.