function checkform()
{
	var subject = document.getElementById('subject');
	var detail = document.getElementById('detail');
	var name = document.getElementById('name');
	var customer_mail = document.getElementById('customer_mail');
	var kod = document.getElementById('kod');
	
	if (subject.value.length!=0 && detail.value.length!=0 && name.value.length!=0 && customer_mail.value.length!=0 && kod.value.length!=0)
	{
		// something is wrong
	return true;
	}
	
	alert('Prosím, vyplňte všetky polia!');
	
	if(subject.value.length==0)
	{
	document.getElementById('comment1').innerHTML = 'Prosím, zadajte subjekt emailu.';
	}else{
	document.getElementById('comment1').innerHTML = '';
	}
	
	if(detail.value.length==0)
	{
	document.getElementById('comment2').innerHTML = 'Prosím, zadajte text emailu.';
	}else{
	document.getElementById('comment2').innerHTML = '';
	}

	if(name.value.length==0)
	{
	document.getElementById('comment3').innerHTML = 'Prosím, zadajte Vaše meno.';
	}else{
	document.getElementById('comment3').innerHTML = '';
	}

	if(customer_mail.value.length==0)
	{
	document.getElementById('comment4').innerHTML = 'Prosím, zadajte Váš email.';
	}else{
	document.getElementById('comment4').innerHTML = '';
	}

	if(kod.value.length==0)
	{
	document.getElementById('comment5').innerHTML = 'Prosím, zadajte kontrolný kód.<br>';
	}else{
	document.getElementById('comment5').innerHTML = '';
	}
	
	return false;

}