Empty popups and style on a GeoJSON layer in Leaflet

Question

I am trying to populate popups on each polygon and style the layer according to type of commodity. Popups are empty and style doesn't work.

Code shown below:

lyrlicences = new L.GeoJSON.AJAX('data/Tzlicences.geojson',{style:stylePolygons, onEachFeature:returnPolygons}).addTo(tzmap);
function stylePolygons(json){
    var att = json.properties;
       if(att.commoditie =='Gold'){
        return {color: 'yellow', weight:3}
       }
   if(att.commoditie =='Copper'){
    return {color: 'brown', weight:3}
   }
  else {
    return {color: 'red', weight:5}
   }  

}
function returnPolygons(json, layer){
  layer.bindPopup(json.properties.commoditie);
}