Reading custom HTML elements using JavaScript is not working in IE

I have some custom elements in my HTML page. To do some modifications on it, I wrote a JavaScript.

It has got some custom elements in it. These elements are added intentionally.

Sample Source:

<div>       
        <br />
     <a name="IDATLQHE"></a>
    <h2 class="subhead" xmlns="">
    <dev>
        <dd>
            <span>abcd</span>
        </dd>

        <rr>
            <span>
                    <a title="google" href="http://google.com">google.com</a>
            </span>
       </rr>                    
    </dev>
    </h2>       
</div>

Output needed:

I want to replace the contents of the <a> element in the <rr> element with the contents of the <dd> element. (The elements <rr>, <dd> and <dev> are the custom elements.)

JavaScript written:

<script type="text/javascript">
 var devs = document.getElementsByTagName('dev');
for(var i = 0, len = devs.length; i < len; i++)
{
    var dev = devs[i],
        h2 = dev.getElementsByTagName('rr'),
        h3 = dev.getElementsByTagName('dd');
    if(h2.length === 1)
    {
        var aa= h2[0],
        aaa=aa.getElementsByTagName('a');
        if(h2.length === 1 && h3.length === 1)
        {
            aaa[0].innerHTML = h3[0].innerHTML;
            h3[0].innerHTML=null;
        }
    }
}
</script>

This script is working fine in Firefox, but not in IE.

Edit:

After adding the HTML elements and adding different class attributes.

<div>       
            <br />
         <a name="IDATLQHE"></a>
        <h2 class="subhead" xmlns="">
         <div class="dummy">
             <div class="dummyy">
                <span>abcd</span>
            </div>

            <div class="dummyyy">
                <span>
                        <a title="google" href="http://google.com">google.com</a>
                </span>
          </div>                
        </div>
        </h2>       
    </div>

Modified Java Script:

  <script type="text/javascript">
    var divs = document.getElementsByClassName('dummy');
    for(var i = 0, len = divs.length; i < len; i++)
    {
        var div = divs[i],
        h2 = div.getElementsByClassName('dummyyy'),
        h3 = div.getElementsByClassName('dummyy');
        if(h2.length === 1)
        {
            var aa= h2[0],
            aaa=aa.getElementsByTagName('a');
            if(h2.length === 1 && h3.length === 1)
            {
                aaa[0].innerHTML = h3[0].innerHTML;
                h3[0].innerHTML=null;
            }
        }
    }

I am still facing the same problem. Its not working for IE(Version 8).

Can any one suggest the changes to be done to make it work in both IE and Firefox?