Warum funktioniert das JavaScript nicht

var CopyrightStatus = "True";  
var CopyrightNotice = "Copyright(C) 2006, BlaBlub Corp."  
var CopyrightInfoURL = "http://www.domain.tld"  


var meta = this.metadata;
var myXMPData = new XML(meta);
myx = new Namespace("adobe:ns:meta/");  
myrdf = new Namespace("http://www.w3.org/1999/02/22-rdf-syntax-ns#");  
mypdf = new Namespace("http://ns.adobe.com/pdf/1.3/");  
myxap = new Namespace("http://ns.adobe.com/xap/1.0/");  
mydc = new Namespace("http://purl.org/dc/elements/1.1/");  
myxapRights = new Namespace("http://ns.adobe.com/xap/1.0/rights/");  
var p = myXMPData.myrdf::RDF.myrdf::Description;
/*
We test whether this element has a value already, if no, we assign it a
value, otherwise we assign it another value.
*/
if (p.mydc::rights.myrdf::Alt.myrdf::li.toString() == "") {  
p += <rdf:Description rdf:about=""  
xmlns:dc="http://purl.org/dc/elements/1.1/"  
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">  
<dc:rights>
<rdf:Alt>
<rdf:li xml:lang="x-default">  
{CopyrightNotice}
</rdf:li>
</rdf:Alt>
</dc:rights>
</rdf:Description>
} else
p.mydc::rights.myrdf::Alt.myrdf::li = CopyrightNotice;
/*
Some elements are converted into attributes, so we need to first test
whether the xapRights:Marked attribute is present, if not, we add it in as an
element; otherwise, if the attribute is present, we update the attribute.
Acrobat changes certain elements into attributes; the xapRights:Marked and
xapRights:WebStatement are two such examples, but dc:rights above is one
that is not changed into an attribute.
*/
if (p.@myxapRights::Marked.toString() == "" ) {  
p += <rdf:Description rdf:about=""  
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"  
xmlns:xapRights="http://ns.adobe.com/xap/1.0/rights/">  
<xapRights:Marked>{CopyrightStatus}</xapRights:Marked>
<xapRights:WebStatement> {CopyrightInfoURL} </xapRights:WebStatement>
</rdf:Description>
} else {
p.@myxapRights::Marked = CopyrightStatus;
p.@myxapRights::WebStatement = CopyrightInfoURL;
}
// Convert myXMPData into a string
myNewXMPStr=myXMPData.toXMLString();
// and assign it to the document metadata
this.metadata = myNewXMPStr;