Bing Maps Api clear a layer
<p>I have a page that works well it loads a Bing Map and creates a layer which is then filled with Polygons.  I then need to reload the JSON data that makes the polygons and this again works, however the data is then added to another layer so appears over the top.  I have tried to delete the layer, clear the layer etc etc but nothing seems to work.</p>

<p>Any idea please.</p>

<p>This is the function that does it all...</p>

<pre><code>        function AddData() {

        dataLayer = new Microsoft.Maps.Layer();

        Microsoft.Maps.loadModule('Microsoft.Maps.GeoJson', function () {
            var featureCollection = Microsoft.Maps.GeoJson.read(json, {
                polygonOptions: {
                    strokeColor: 'LightSkyBlue',
                    strokeThickness: 2
                }
            });

            for (var i = 0; i &lt; featureCollection.length; i++) {
                var fillColour = featureCollection[i].metadata.FillColor;
                featureCollection[i].setOptions({ fillColor: fillColour });

                Microsoft.Maps.Events.addHandler(featureCollection[i], 'click', displayClickBox);
                Microsoft.Maps.Events.addHandler(featureCollection[i], 'mouseover', displayMouseOverBox);
                Microsoft.Maps.Events.addHandler(featureCollection[i],'mouseout', displayMouseOut);
                dataLayer.add(featureCollection[i], 0);
            }
            map.layers.insert(dataLayer);
        });
    }

        var getJson = function () {
        var onContentComplete = function (response) {
            //Load the JSON data into the local variable for use latter in the project...
            json = response.data;
            //load the map now that we have the polygon data...
            AddData();
        };

        var onError = function (reason) {
            //An error has occured so display a message to the user...
            $scope.error = "Server communication error please try again...";
            //Log the error to the console for admin debug...
            console.log(reason.data);
        };

        //Load the JSON for the map polygons into memory ready for display...
        $http.get("../JSON/MapData.json")
            .then(onContentComplete, onError);
    }
</code></pre>

<p>As I have said I have tried to clear the layer first using</p>

<pre><code>dataLayer.clear();
</code></pre>

<p>But that seems to do nothing.</p>

<p>Help please as I have been working at this for hours now.</p>

<p>Thanks</p>

<p>Cliff.</p>