What does this error mean?

[Universal]

I get follow error trying to get categories from my blog through BlogDesk

Error getting categories
XML Parsing Error: More than one root node found at character 11

What does it mean and how to resolve this one?

[Johannes]

I need more info. Do the following:

1) Enter a Debug-File under Extras/Options in the tab 'Extras'.
2) Try to get the categories.
3) Send me the Debug-File (don't worry, Login/Password are masked) to [support at blogdesk dot org]
4) You can now delete the entry for the Debug-File in the options.

[Johannes]

Ok, I got your file.

WordPress internally calls a file named class-IXR.php - but on your server this file is called class-ixr.php. If your server is case-sensitive it won't find the file (because ixr <> IXR). Solution: rename the file from ../wp-includes/class-IXR.php to ../wp-includes/class-ixr.php.

[Universal]

Thank you very much
The problem was in xmlrpc.php file, the code contained string with 'class-IXR.php'
thanks again