//kontroll form
function kontroll(form){
 var error = 0;
 var message;

 var tag = form.ANREISE_TAG.selectedIndex+1;
 var monat = form.ANREISE_MONAT.selectedIndex+1;
 var jahr = form.ANREISE_JAHR[form.ANREISE_JAHR.selectedIndex].name; 
 var tag_ab = form.ABREISE_TAG.selectedIndex+1;
 var monat_ab = form.ABREISE_MONAT.selectedIndex+1;
 var jahr_ab = form.ABREISE_JAHR[form.ABREISE_JAHR.selectedIndex].name; 

 if(tag<10) tag = "0"+tag;
 if(monat<10) monat = "0"+monat;
 var anreise = jahr+monat+tag;
 
 if(tag_ab<10) tag_ab = "0"+tag_ab;
 if(monat_ab<10) monat_ab = "0"+monat_ab;
 var abreise = jahr_ab+monat_ab+tag_ab;

 if(anreise>abreise){
  error++;
  message = "The arrival is later than the departure";
  } else if (anreise==abreise){
    error++;
	message = "The arrival and the deperture are at the same day";
    }
		
 if(error == 0){ return true; } 
 else { alert(message); return false; }  
}