function not being called first time script runs

Question

I am new to JavaScript and I have beginners grip on the concepts I have a function that gets the label from a kml and displays it on screen (some of the clustering part of this function was supplied by someone on S/O). it works perfectly for all the kmls that are loaded except the First one.

I am sure that the problem is something to do with a variable and its scope, but for the life of me i cannot see where or how I am getting an error, I correction to the code would be a great help, but correction to my understanding (or lack there of) just as helpful.

many thanks in adavance

here is the code

EDIT 1) I have changes the function getlabel a number of times and the changes are only seen on kmls loaded outside of the first ajax call shown below. I don't for the life of em understand why this is happening. It may be a context issue, however this is beyond my understanding of the topic

var tripid=1;
var myStyles;
var cfarmerid;
var navigate=true;
var edit=false;
var vectors;
var polyControl;
var bound=false;
var mycluster;
var label=" ";



$(document).ready(function(){
    $.ajax({
        type: "POST",url: "temp.php",dataType: "json",
        error: function(e){
            alert('Error: '+e);
        },  

        success: function (data) {
        if(data[0]==="not"){
               window.location = "http://www.g4ema.com/index.html";
            }
            maxlat=data[0];
        maxlon=data[1];
            minlat=data[2];
        minlon=data[3];
        tripid=parseInt(data[4]);



    var bbox=new OpenLayers.Bounds();
        bbox.extend(new OpenLayers.LonLat(minlon,minlat));
        bbox.extend(new OpenLayers.LonLat(maxlat,maxlon));
        bbox.toBBOX();

        map = new OpenLayers.Map("map");
    //var layer=  new OpenLayers.Layer.OSM();


         mycluster = new OpenLayers.Strategy.Cluster(
         {
            threshold: 2, // single clusters are shown as features
            shouldCluster: function(cluster, feature) 
            {
            if (feature.geometry.CLASS_NAME === "OpenLayers.Geometry.Point" &&
                cluster.cluster[0].geometry.CLASS_NAME === "OpenLayers.Geometry.Point") {
                    return OpenLayers.Strategy.Cluster.prototype.shouldCluster.apply(this, arguments);
                } else {
                    return false;
                }
            }
        });


    var layer = new OpenLayers.Layer.Google(
            "Google Hybrid",
            {type: google.maps.MapTypeId.HYBRID, numZoomLevels: 20});
            layer.wrapDateLine=false;
        map.addLayer(layer);

     myStyles = new OpenLayers.StyleMap({ 
         "default": new OpenLayers.Style({ 
            strokeColor: "#00ffff", 
            strokeWidth:5, 
            strokeOpacity:1, 
            fillColor:"#003399", 
            fillOpacity: 1,
            labelYOffset: 15,
            pointRadius: 4,
            label:"${getLabel}", 
            fontColor:"#ff0000"
        }, {
            context: {
                getLabel: function (f) {
                    label=" ";
                    if (f.cluster) { // is a cluster
                        if (f.cluster[0].attributes.label!==" ") {
                            label= " " + f.attributes.count  + " " +
                                f.cluster[0].attributes.label;
                        } else {
                            label= " " ;//+ f.attributes.count + "init";
                        }
                    } else { // is not cluster
                        if (f.attributes.label!==" ") {
                            label= " " + f.attributes.label;

                        }else{
                            label=" ";
                        }
                    }
                    if(!label){label=" ";}
                    return label;
                }

            }
    })
});




      kmlLayer = new OpenLayers.Layer.Vector("Trip", {
                styleMap: myStyles,
                    projection: map.displayProjection,      
                    strategies: [new OpenLayers.Strategy.Fixed(),mycluster],
                    protocol: new OpenLayers.Protocol.HTTP({
                        params:{ tripid:tripid},    
                    url: "kml2.php",
                    readWithPOST:true,
                    //{userid:userid,tripid:tripid},
                    format: new OpenLayers.Format.KML({
                                extractStyles: true,
                                extractAttributes: true             
                            })          
                        })          
                    });

            map.addLayer(kmlLayer);

             var clat=(parseFloat(minlat)+parseFloat(maxlat))/2;
                var clon=(parseFloat(minlon)+parseFloat(maxlon))/2;
                var lonlat = new OpenLayers.LonLat(clon,clat).transform(new OpenLayers.Projection("EPSG:4326"),new OpenLayers.Projection("EPSG:900913"));
                map.setCenter(lonlat);
                map.zoomTo(15);

Answer 1

First of all, I don't see the advantage of declaring the label variable with global scope in the context of the code you've shared. Since you're returning a label from the getLabel function then I think you should just declare var label; at the top of the getLabel function and return the value of that local variable from the function.

Second, the only way I can see that "undefined" would be returned from getLabel is if f.attributes.label is undefined. I would try a code block such as:

} else { // is not cluster
   if (f.attributes.label != null && typeof(f.attributes.label != "undefined") {
   // if (f.attributes.label) {   // alternate simpler if statement
      label= " " + f.attributes.label;
   } else {
      label = " ";
   }
}

Answer 2

For anyone looking this with the same problem,

The above code is faultless, the reason this wasn't working is I was calling another function later in the $document.ready() and this was refining the mycluster variable. I am very sorry for those you have looked at this and couldn't see the problem.

but the above code will work FINE