RadGrid populate drop down in insert/edit mode

jQuery's documentation states:

[jQuery.val] checks, or selects, all the radio buttons, checkboxes, and select options that match the set of values.

This behavior is in jQuery versions 1.2 and above.

You most likely want this:

$("._statusDDL").val('2');

The approach described by Program.X is very good. This, of course, works if you're using a RadCombobox inside of a GridTemplateColumn in RadGrid.

RadGrid also provides a built-in GridDropDownColumn that can automatically render a RadCombobox during edits. If you choose to use the built-in column type, you need to programmatically set the client-side event handlers for the rendered RadGrid, like this:

protected void RadGrid1_ItemCreated(object sender, Telerik.Web.UI.GridItemEventArgs e)
{
    //Find GridEditableItems when in Edit mode
    if (e.Item is GridEditableItem && e.Item.IsInEditMode)
    {
        //Get reference to item (i.e. Row)
        var item = e.Item as GridEditableItem;

        //Get reference to auto-generated RadCombobox in
        //specific column (in this case, a column called Title)
        var rcb = item["Title"].Controls[0] as RadComboBox;
        if (rcb == null)
            return;

        //Customize the RadCombobox properities
        rcb.OnClientSelectedIndexChanged = "onselectedindexchanged";
    }
}

Where "onselectedindexchanged" is the name of a client-side JavaScript function on your page designed to handle the RadCombobox event.

Either of these approaches should enable you to achieve your goal.