change selecteditem of dropdownlist after binding
<p>i have a droplist in page that i bind this with code</p>

<pre><code> Category catObj = new Category();
    dropCat.DataSource = catObj.GetAllCategory();
    dropCat.DataTextField = "Title";
    dropCat.DataValueField = "CategoryID";
    dropCat.DataBind();
</code></pre>

<p>i want change selected  item of droplist with ths code</p>

<pre><code>dropCat.SelectedIndex = Convert.ToInt32(catObj.ParentId);
</code></pre>

<p>but this code cant change the selected item
please help me 
thank you all</p>
