XML-RPC question

[eluser]capypara[/eluser]
this question is in regards to the following link:
http://ellislab.com/codeigniter/user-gui...mlrpc.html

i copied the codes and tried running it, but i got this error

XML data received was either invalid or not in the correct form for XML-RPC. Turn on debugging to examine the XML data further.

i did not change anything in the codes, so i am wondering what went wrong........