问Openlayers:缩放WFS有时会返回到第一个缩放级别

EN

var renderer = OpenLayers.Util.getParameters(window.location.href).renderer;
renderer = (renderer) ? [renderer] : OpenLayers.Layer.Vector.prototype.renderers;
wfsLayer = new OpenLayers.Layer.Vector("Dakvlakken", { 
  renderers: renderer,
  displayInLayerSwitcher: true,
  strategies: [new OpenLayers.Strategy.BBOX()],
  filter: new OpenLayers.Filter.Comparison({ 
          type: OpenLayers.Filter.Comparison.EQUAL_TO,
          property: "adres_id",
          value: startAdresID}),
  protocol: new OpenLayers.Protocol.WFS({ 
    url: "http://MyIP/geoserver/wfs",
    featureType: "full",
    srsName: "EPSG:28992",
    geometryName: "geom_rd"
  })
});

function changeFilter(newValue, x, y, adres)
{ 
    wfsLayer.destroyFeatures();
    filter = new OpenLayers.Filter.Logical(
    { 
      type: OpenLayers.Filter.Logical.AND, 
      filters: [ 
        new OpenLayers.Filter.Comparison(
        { 
            type: OpenLayers.Filter.Comparison.EQUAL_TO, 
            property: "adres_id", 
            value: newValue 
        }), 
        new OpenLayers.Filter.Spatial(
        { 
            type: OpenLayers.Filter.Spatial.BBOX, 
            value: new OpenLayers.Bounds(x-50, y-50, x+50, y+50), 
            projection: "EPSG:28992" 
        }) 
      ]  
    });

    wfsLayer.filter = filter;
    wfsLayer.refresh({force: true});
  }
}