How to change gridview header on row created.

protected void grvUserThread_RowCreated(object sender, GridViewRowEventArgs e)
{
try
{
if (e.Row.RowType == DataControlRowType.Header)
{
GridViewRow headerRow = e.Row;
Label lb = new Label();
lb = (Label)e.Row.FindControl("lblabc");
lb.Text = "Thread: " + Thread;
}
}