How can I compare two .xps files?

I'm currently using TC 8.70

I do have to compare two .xps files. Since they are inherently xml files, I thought I could follow the procedure outlined in the Help to compare XML files from a script. However, when creating the checkpoint the following Exception is raised:

The document is invalid. Error: An invalid character was found in text content.



The code I'm using is directly from the TC Help manual:

function CreateXMLDemo()

{

  var XMLDoc;



  // Checks if NewXMLCheckpoint already exists in the Stores | XML collection.

  if (! XML.Contains("NewXMLCheckpoint"))

    {

    // Creates an IXMLDOMDocument object.

    XMLDoc = Sys.OleObject("Msxml2.DOMDocument.6.0");

    XMLDoc.async = false;

    // Loads data form the XML file to the IXMLDOMDocument object.

    var TestingDirectory = Application.GetTestingDirectory("HB003\\");

    var fileExpected = TestingDirectory + "eReport.xps";

    XMLDoc.load(fileExpected);



    // Creates NewXMLCheckpoint and checks if the creation is successful.

    if (XML.CreateXML("NewXMLCheckpoint", XMLDoc)) //--> This is where it fails

}



Thanks in advance for your help