System.Reflection.TargetInvocationException after publishing xbap

Question

recently i've started learning C# and encountered a problem with my WPF application after publishing it.

First, let me explain what the application should do: Read the xml-file "testxml.xml", and write the names given there in a ListBox. The xml-File lies in \myProject\bin\Debug.

My code:

public partial class Page1 : Page
        {
        private string path = System.IO.Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location) + @"\testxml.xml";
        List myList = new List();


    public Page1()
    {
        InitializeComponent();
        ReadXML(path, myList,ListBox1);
    }


    public static void ReadXML(string path, List<TestXML> myList, ListBox ListBox)
    {
        if (File.Exists(path))
        {
            XmlSerializer deserializer = new XmlSerializer(typeof(List<TestXML>));
            TextReader reader = new StreamReader(path);
            object obj = deserializer.Deserialize(reader);
            myList = (List<TestXML>) obj;
            reader.Close();
        }

        for (int i = 0; i < myList.Count; i++)
        {
            ListBox.Items.Add(myList[i].Name);
        }

    }

}

This works fine in debug mode. So, I tried to publish it. Therefore, I've included the xml-file in my project and changed its settings "Build Action" to "Content" and "Change to Output Directory" to "Copy Always". Furthermore, I changed its "Publish Status" from "Data File" to "Include" in my project properties. I published it via publish wizard to "C:\user\" and select "From a CD-ROM or DVD-ROM".

This gave me an xbap-File and an "Application Files"-Folder in "C:\users\". The xml-file is available under "\Application Files\MyProject_1_0_0_x\bin\Debug". But when I execute the xbap-File, it gives me a huge error that starts with

"System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation."

My suggestion so far is the directory of the xml-file, which perhaps doesn't work after publishing. What would be the correct directory? Or is there another mistake I'm not aware of?

Any help is greatly appreciated!