function showCoaching() {

    if(document.getElementById('tx_pilmailform_pi1[checkbox][change_coaching]').checked) {

      document.getElementById('coaching').style.display = 'block';
      document.getElementById('teams').innerHTML = '... und trainiere folgende Mannschaft(en)';  }

    else
        {
      document.getElementById('coaching').style.display = 'none';
      document.getElementById('teams').innerHTML = '';   }

}