How to set focus in a GridView

protected void GridViewIns()
{
   try
    {
      Ds = objBLL.GetData();
      if (Ds.Tables[0].Rows.Count > 0)
        {
          gvIns.DataSource = Ds;
	  gvIns.DataBind();
	}            
    }
    catch (Exception ex)
     {
       Message.Text = ex.Message;
     }
}
protected void gvInst_RowEditing(object sender, GridViewEditEventArgs e)
{
   gvIns.EditIndex = e.NewEditIndex;
   GridViewIns();
   gvIns.Rows[e.NewEditIndex].FindControl("txtIns").Focus();
}
protected void gvIns_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
    gvIns.PageIndex = e.NewPageIndex;
    GridViewIns();
}