title: OpenLayers => feature is null
body: <p>This is my GeoJSON result. <a href="http://pastebin.com/5cnYi9J1" rel="nofollow">PasteBin</a>
  But when I load it, the result I get in  firebug is feature is null. Why's that, are there any errors in my result? The coords in the JSON is written in projection WGS84, and in the code I also have set the externalProjection as WGS84. So why do I get the return "feature is null"?
  The code I use to manage my map is :</p>
  
  <pre><code>$(document).ready(function() {
  var wgs84 = new OpenLayers.Projection('EPSG:4326');
  var layer = null;
  var map = new OpenLayers.Map('map',{projection: wgs84});
    layer = new OpenLayers.Layer.OSM( "Simple OSM Map");
      var baseProjection = layer.projection; 
    map.addLayer(layer);
    map.setCenter(new OpenLayers.LonLat(10,10), 4);
    map.events.register("moveend", null, function(){
  
        if(map.zoom == 10)
        {
          var bounds = map.getExtent();
          console.log(bounds);
          var ne = new OpenLayers.LonLat(bounds.right,bounds.top).transform(map.getProjectionObject(),wgs84);
          var sw = new OpenLayers.LonLat(bounds.left,bounds.bottom).transform(map.getProjectionObject(),wgs84);
          var vectorLayer = new OpenLayers.Layer.Vector();
          map.addLayer(vectorLayer);
          $.getJSON('ajax.php?a=markers&amp;type=json&amp;sw=('+sw.lon+','+sw.lat+')&amp;ne=('+ne.lon+','+ne.lat+')',function(data){
          //$.getJSON('test.json',function(data){
              var geojson_format = new OpenLayers.Format.GeoJSON({
                  'externalProjection': wgs84,
                  'internalProjection': baseProjection
                  });
              vectorLayer.addFeatures(geojson_format.read(data));
          });
          }
      });
  });
  </code></pre>