百度地图Lable：如何去掉讨厌的背景色

/*标签*/
function createLable(map, point, content) {
    var opts = {
        position: point,   
        offset: new BMap.Size(-5, 10)   
    }
    var label = new BMap.Label(content, opts);
    label.setStyle({
        color: "#000",
        border: "0px",
        backgroundColor: "0.000000000001",  //通过这个方法，去掉背景色
        fontSize: "12px",
        height: "20px",
        lineHeight: "20px"
    });
    map.addOverlay(label);
    return label;
}