Custom sort, help required

var dsc = app.defaultSortCriteria;



var sc1 = new SortCriterion("sortByCity", "string","http://iptc.org/std/Iptc4xmpCore/1.0/xmlns/", "Iptc4xmpCore:CreatorContactInfo/Iptc4xmpCore:CiAdrCity","City");



dsc.push(sc1);



try{



var sortHandler = new ExtensionHandler("sortHandler");



}catch(e){$.writeln(" New Extension Handler " +e.message);}



try{



app.registerExtension(sortHandler);



}catch(e){$.writeln("Registering Handler " +e.message);}



app.registerPrefix( "bridge:sorts:", sortHandler);



try{



var customInfoset = new Infoset("customInfoset", dsc);



}catch(e){$.writeln("New Infoset " + e.message);}



try{



app.registerInfoset(sortHandler, customInfoset);



}catch(e){$.writeln("Register Infoset " + e.message);}







var mySortObj = {};



mySortObj.name = "sortByCity";



mySortObj.type= "string";



mySortObj.reverse = false;



var mySortsArray = [];



mySortsArray.push(mySortObj);



try{



app.document.sorts = mySortsArray;



}catch(e){alert(e.message);}