Layers model empty

loadlayers.js

initBaseOverlays: function () {
    var settings = this.get("settings"),
      layers = this.get("content"),
      baseOverlays,
      apiKey = settings.apiKey,
      overlayKey,
      overlay,
      subtype,
      result = {};

    layers.then(function (loadedLayers) {
      // loadedLayers is empty
      baseOverlays = loadedLayers.filterProperty("type", "base");
      
      for(overlayKey in  baseOverlays) {
        overlay = baseOverlays[overlayKey];
        type = overlay.get("type");
        overlayKey = overlay.get("id");

        if(overlayKey !== "none" && type === "base") {
          result[overlayKey] =  new L.BingLayer(apiKey, { 
            name: overlay.get("label") , 
            type: overlay.get("subtype") 
          });        
        }
      }

      this.set("baseLayers", result);
    });
    
    this.set("defaultBaseLayer", settings.defaults.baseLayer);
  }.observes("content")