function okresy(errorId) {
  var krajeElement = document.getElementById('kraj');
  
  if (krajeElement.selectedIndex)
    changeText('hlaska' + errorId, '<small class="green">ok</small>');
  else {
    changeText('hlaska' + errorId, '<small class="red">nezvoleny kraj</small>');
  }
  
  changeText('hlaska' + (errorId+1), '<small class="red">nezvoleny okres</small>');
  
  xmlhttp = createRequest();
  
  xmlhttp.open('get', '/ajax/okresy/okresy.php?kraj='+krajeElement[krajeElement.selectedIndex].value);
  xmlhttp.onreadystatechange = function() {
    if(xmlhttp.readyState == 4){
    
  		if (xmlhttp.status == 200){
        var response = xmlhttp.responseText;

        clearOptions('okres');
        addOption('okres', 0, 'zvoľte okres');
  
        if(response.indexOf('|') != -1) {
          update = response.split('|');
            for(i=1;i<update.length;i+=2) {
              addOption('okres', update[i], update[i+1]);
            }
        }
  
        
  		}
  		else
  		  alert(xmlhttp.status);
    }
  }
  xmlhttp.send(null);
}