Error On Loading ArcGISDynamicMapServiceLayer

Question

Can you please take a look at this demo ​and let me know why I am getting this error

Uncaught ReferenceError: ArcGISDynamicMapServiceLayer is not defined

As you can see I have registered the  "esri/layers/ArcGISDynamicMapServiceLayer", but still getting the error

var map;
var layerOpacity = 0.25;
require(["esri/map",
    "esri/layers/ArcGISDynamicMapServiceLayer",
    "dojo/parser",
    "dojo/dom",
    "dojo/on",
    "dojo/ready",
    "dojo/domReady!"], function (
Map,
ArcGISDynamicMapServiceLayer,
parser,
dom,
on,
ready) {
    map = new Map("mapDiv", {
        center: [-126.687482, 54.793577],
        zoom: 5,
        basemap: "topo"
    });
});
 var appLayer    = new ArcGISDynamicMapServiceLayer("http://renewablestoolbox.biol.sfu.ca/rorapp/rest/services/RORApp/MapServer/22");
map.addLayer(appLayer);

thejuskambi · Accepted Answer

The require function is closed just before where you initialize the var appLayer.

you need to write code within that block