why Cannot create XmlPullParser?

Hello

I am trying to convert from xml file that i created back to Object.

[b]

XStream xstream = new XStream();
xstream.alias("Model", Model.class);
String xml = xstream.toXML(bigMaze);
System.out.println(xml);
		
Model bigMaze9 = (Model) xstream.fromXML(xml);
int x9 = bigMaze9.solveDomain();
System.out.println(x9);[/b]

that what i get:
Exception in thread “main” com.thoughtworks.xstream.io.StreamException: Cannot create XmlPullParser
at com.thoughtworks.xstream.io.xml.AbstractXppDriver.createReader(AbstractXppDriver.java:56)
at com.thoughtworks.xstream.XStream.fromXML(XStream.java:1040)
at com.thoughtworks.xstream.XStream.fromXML(XStream.java:1031)
at controller.boot.Run.main(Run.java:46)

please help