Adding an AD using javascript

Question

I am making an HTML5/JavaScript Win 8 app and trying to add an AD on my HTML page from a js file. I am using the following code:

adDiv= document.createElement('div');

adDiv.setAttribute("id", "myAd2");

adDiv.setAttribute("data-win-control", "MicrosoftNSJS.Advertising.AdControl");

adDiv.setAttribute("data-win-options", "{applicationId: 'd25517cb-12d4-4699-8bdc-52040c712cab', adUnitId: '10043105'}");

adDiv.setAttribute("style", "width: 150px; height: 120px; border:solid 2px #000");

document.getElementById("xyz").appendChild(adDiv);

where div id="xyz" exists.

Yet, the AD div appears to be blank. Its just the black border that is visible.

The AD looks and works fine when directly placed in the HTML file:

<div id="myAd" style="width: 250px; height: 250px; z-index: 1" data-win-control="MicrosoftNSJS.Advertising.AdControl" data-win-options="{applicationId: 'd25517cb-12d4-4699-8bdc-52040c712cab', adUnitId: '10043105'}"> </div>

Can't ADs be added from a js file? This seems weird.