my code is the following:
the Read() method positions the cursor on the <condition> tag (verified
with debugger).

XmlReaderSettings s = new XmlReaderSettings();
s.IgnoreComments = true;
s.IgnoreWhitespace = true;
s.IgnoreProcessingInstructions = true;

using (XmlReader reader = XmlReader.Create("class.xml", s))
{
    reader.Read();
    reader.ReadElementContentAsString();
}

the xml is:

..
<condition> test </condition>
..

Then an Exception is thrown which reads (translated from german):

The 'ReadElementContentAs()' method is not allowed to be called on
elements with sub-elements. line 7, position 12.

I do not understand this, in <condition> there is definitely no sub-element.