[Users] rules on cluster features

[François Boussuges]

Hello,
I have a cluster WFS layer and I apply an variable 'radius' and 
'fillcolor' with a context:
var context = {
   
    fillColor: function(feature) {
        if(feature.cluster) {
            sens_hor= parseFloat(0)
            for(var c = 0; c < feature.cluster.length; c++)
            
sens_hor=sens_hor+parseFloat(feature.cluster[c].attributes.SPIRALE_GOUSSE_HORAIRE)
            result=sens_hor/feature.cluster.length
            if(result > 50) return "#990000";
            if(result<=50) return "#000099";}

        } ,
    label: function(feature) {
        if(feature.cluster) {
            sens_hor= parseFloat(0)
            for(var c = 0; c < feature.cluster.length; c++)
            
sens_hor=sens_hor+parseFloat(feature.cluster[c].attributes.SPIRALE_GOUSSE_HORAIRE)
            result=sens_hor/feature.cluster.length
            return result;}},
    radius: function(feature) { var pix = 3; if(feature.cluster) { pix =
        Math.min(feature.attributes.count, 7) *2; } return pix;}};

    var defStyle1 = new OpenLayers.Style({
        pointRadius: "${radius}",
        fillColor: "${fillColor}",
        fillOpacity:1,
        strokeColor: "#FFFF00",
        strokeWidth: 1,
        strokeOpacity: 1 }
    /* context pour le cluster */
    ,{ context: context}
   
           
    );

This is ok but I want to use Openlayers.Rules and filter to add rules on 
my style and display the legend of my layer (with GeoExt.LegendPanel).
But when I try to add rule with 'label' propertie the color is not display:

defStyle1.addRules =([new OpenLayers.Rule( {
        title: "<50% spirale horaire",
        context: context,
        symbolizer : {
        fillColor : "#990000",
            },
       
    filter : new OpenLayers.Filter.Comparison({
        type : OpenLayers.Filter.Comparison.LESS_THAN_OR_EQUAL_TO,
        property: "${label}",
        value:50
       
    })
    }),     new OpenLayers.Rule( {
        title: ">50% spirale antihoraire",
        context: context,
        symbolizer : {
        fillColor : "#000099"
    },
    filter : new OpenLayers.Filter.Comparison({
        type : OpenLayers.Filter.Comparison.GREATER_THAN,
        property: "${label}",
        value:50
    })
    })]);

Have you an idea?

Thank you