ArcGIS for JS 画图为什么不显示

[namedScott]

感觉是symbol定义出了问题，但是具体找不到。有没有大佬帮我看看

<script>
        var map;
 
        require([
            "esri/map", "esri/geometry/Point", "esri/SpatialReference",
            "esri/symbols/SimpleMarkerSymbol", "esri/graphic","esri/symbols/SimpleLineSymbol","esri/geometry/Polygon"
        ], function(Map, Point, SpatialReference, SimpleMarkerSymbol, Graphic) {
            map = new Map("map", {
                basemap: "topo",
                center: [0, 45],
                zoom: 13
            });
			map.on("load", function() { drawPolygon; });
			function drawPolygon(){
				var points = [[0,0],[0,45],[45,45],[45,0],[0,0]];
				var polygon = new Polygon(new SpatialReference({wkid:4326}));
				polygon.addRing(points);
				var simpleLineSymbol = new SimpleLineSymbol(SimpleLineSymbol.STYLE_SOLID,new Color([58,27,177]),23);
				var graphic = new Graphic(polygon,SimpleLineSymbol);
				
				map.graphics.add(graphic);
			};
        });
</script>