XSLT Transformation error: Non-canonical structure of element name

Good day experts,

I have recently started using xslt, and came upon the following demo in the sdn.

http://wiki.sdn.sap.com/wiki/display/ABAP/XMLXSLTwith+ABAP

I have retrieved the example xml files from airplus.com, as per the instructions, and implemented the code.

When I test the xslt transformation in se80, it transforms correctly.

However, when I run the program, I get the following error.

CX_XSLT_FORMAT_ERROR

Transformation error: Non-canonical structure of element name XML_OUTPUT

Is there an error in the example that I am not aware of?

Thanks in advance,

Johan Kriek