how to get brush name?

i had been getting the name of  part of the brush.but some of brush name unable to get.the code as fallow:

var param = get_brush_param(); 

// examples 

// show all (almost all) brush props 

alert(obj_to_str(param), "currentTool options"); 

function obj_to_str(obj){var str = ""; for (var p in obj) if(obj.hasOwnProperty(p))try{str+=p+"::"+obj

+"\n";}catch(e){};

      logInfo( str);

    return str;} 

////////////////////////////////////////////////////////////////// 

function get_brush_param() 

    { 

    try { 

        var r = new ActionReference(); 

        r.putProperty(stringIDToTypeID("property"), stringIDToTypeID("tool")); 

        r.putEnumerated(stringIDToTypeID("application"), stringIDToTypeID("ordinal"), stringIDToTypeID("targetEnum")); 

        var d = executeActionGet(r); 

        var options = d.getObjectValue(stringIDToTypeID("currentToolOptions"));   

        var ret = new Object(); 

   //  try { var brush = options.getObjectValue(charIDToTypeID("CrpO")); } catch(e) { alert("Current tool not brush!"); return ret; }  

     try { var brush = options.getObjectValue(stringIDToTypeID("brush")); } catch(e) { alert("Current tool not brush!"); return ret; }  

  // alert( options.count);

  //  alert( brush.count);

        for (var i = 0; i < brush.count; i++) 

            { 

            var key = brush.getKey(i); 

            var type = brush.getType(key); 

            var val = undefined; 

            switch (type)  

                { 

                case DescValueType.BOOLEANTYPE:    val = brush.getBoolean(key); break; 

                case DescValueType.DOUBLETYPE:     val = brush.getDouble(key);  break;   

                case DescValueType.INTEGERTYPE:    val = brush.getInteger(key); break; 

                case DescValueType.ENUMERATEDTYPE: val = typeIDToStringID(brush.getEnumerationValue(key)); break; 

                case DescValueType.UNITDOUBLE:     val = brush.getUnitDoubleValue(key); break; // not quite right 

                  case DescValueType.STRINGTYPE: val = brush.getString(key); break;  

              //  case DescValueType.REFERENCETYPE: val = getReference(brush.getReference(key)); break;  

                default: val =  brush.getType(key).toString();

                } 

            if (val != undefined)  

                { 

                var name = typeIDToStringID(key); 

                if (!name) name = typeIDToCharID(key); 

                if (typeof(val) == "string") 

                    eval("ret." + name +"='"+val+"'");  

                else 

                    eval("ret." + name +"="+val);  

                } 

            }                 

        return ret; 

        } 

    catch (e) { alert(e); } 

    } 

function logInfo(Txt){ 

var file = new File(Folder.desktop + "/too_brush1.txt"); 

file.open("w", "TEXT", "????"); 

file.seek(0,2); 

$.os.search(/windows/i)  != -1 ? file.lineFeed = 'windows'  : file.lineFeed = 'macintosh'; 

file.writeln(Txt); 

file.close(); 

}; 

this is successful.

this is fail,i can't get the name.