In the XML example files, the schema reference does not point to the current version of the schema (2.1) but to the version 2.0. I suggest fixing the scham location link in the example messages.
@Jonas: The schema location attribute actually refers to kind of a local file path. To avoid confusion I suggest the schemaLocation on all example files to the valid current scheme URL, i.e. currently http://www.datex2.eu/schema/2/2_1/DATEXIISchema_2_2_1.xsd - for release 2.2 it would subsequently be http://www.datex2.eu/schema/2/2_2/DATEXIISchema_2_2_2.xsd.