in grid view having radio button then how to keep them enabled fasle on page load and enabled true on link buton which is present in same grid vie

protected void grdUrgentItem_RowDataBound(object sender, GridViewRowEventArgs e)
   {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                 //make enable false
                 CheckBox chk = (CheckBox )e.Row.FindControl("chkid");
                 chk.Enabled = false;
            }
   }

protected void grdUrgentItem_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            //make enable true
            GridViewRow row = (GridViewRow)(((LinkButton)e.CommandSource).NamingContainer);
                 CheckBox chk = (CheckBox )row.FindControl("chkid");
                 chk.Enabled = true;
        }