datagrid sort event fires twice

The datagrid sort event fires twice with the result of this being the order does not change. The asc/desc order switches on the first event and then switches on the second time which actually sets it back to the original order. The basic code pieces are:

protected int BindResultsToDatagrid(string sortExpression)
{
searchResultsDataSet =(DataSet)Session{"searchResultsDataSet"];
if (sortExpression.Length > 0)
{
searchResultsDataSet.Tables[0].DefaultView.Sort = sortExpression;

Session["searchResultsDataSet"] = searchResultsDataSet;
}
searchResults.DataSource = null;
searchResults.DataBind();

searchResults.DataSource = searchResultsDataSet.Tables[0].DefaultView;
searchResults.DataBind();
return searchResultsDataSet.Tables[0].DefaultView.Count;
}

protected void searchResults_SortCommand(object source, System.Web.UI.WebControls.DataGridSortCommandEventArgs e)
{
string sortExpression = (string)Session["sortExp"];
string sortDirection = (string)Session["sortDir"];

if (sortExpression != e.SortExpression)
{
sortExpression = e.SortExpression;
sortDirection = "asc";
}
else
{
if (sortDirection == "asc")
sortDirection = "desc";
else
sortDirection = "asc";
}

Session["sortExp"] = sortExpression;
Session["sortDir"] = sortDirection;
BindSearchResultsToGrid(sortExpression + " " + sortDirection);
}

I actually copied this code from the net, and I'm surprised it's out there and doesn't work. Can anyone help?

can you show me the Page Load event?there might be something happening there that's causing the sort to fire twice.

Here's the page load:

private void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
}
}

...not much help.

I got it figured out! I had OnSortCommand="searchResults_SortCommand" on the ascx page for the datagrid and this.searchResults.SortCommand += new DataGridSortCommandEventHandler(searchResults_SortCommand); in the code behind.