After a night slogging, i found my solution;<br>
I'd like to share my solution and any suggetion is appreciated.<br>
I've created a function to add the (KML)  vector layer;<br>
<pre>     function AddLayer()
        {
                // If layer (kml_layer) already exists, remove it before adding the new one
                if (kml_layer) 
                { 
                map.removeLayer(kml_layer); 
                //kml_layer.destroyFeatures();          // not sure if this is necessary. Works well without it.
                }       
                
                // Get file name (.kml file) 
                filename = document.getElementById('theFile').value;
                
                kml_layer = new OpenLayers.Layer.Vector("KML", {
                        projection: map.displayProjection,
                        strategies: [new OpenLayers.Strategy.Fixed(),
                        new OpenLayers.Strategy.BBOX({resFactor: 1.1}),
                        //new OpenLayers.Strategy.Cluster()],           // only usefull if you want to cluster your markers
                        protocol: new OpenLayers.Protocol.HTTP({
                                url: filename,
                                format: new OpenLayers.Format.KML({
                                        extractStyles: true,
                                        extractAttributes: true,
                                        maxDepth: 10
                                })
                        })
                });
                
                map.addLayer(kml_layer);
        }</pre><br>
Also added the function to the 'onClick' event of the button;<br>
<pre><input type="button" value="Show Markers" onClick="AddLayer()"></pre><br>
The hardest part was to find the right way to remove an existing layer. Tried several examples but this one works well.<br><br>



        
        
        
<br/><hr align="left" width="300" />
View this message in context: <a href="http://osgeo-org.1560.n6.nabble.com/Problem-dynamic-loading-a-KML-file-refresh-tp5015133p5015310.html">Re: Problem dynamic loading a KML file (refresh)</a><br/>
Sent from the <a href="http://osgeo-org.1560.n6.nabble.com/OpenLayers-Users-f3910695.html">OpenLayers Users mailing list archive</a> at Nabble.com.<br/>