function IsValidAction( actionForm, errorMessage )
{
	if ( actionForm.title.value=='' || actionForm.year.value=='' || actionForm.time.value=='' || actionForm.week_day.value=='' || actionForm.place.value=='' )
		{
			notFilled = ( actionForm.title.value == '' )? 'název akce' : '';
			notFilled += ( notFilled && ( actionForm.year.value=='' || actionForm.time.value=='' || actionForm.week_day.value=='' || actionForm.place.value=='' ) )? ', ' : '';
			notFilled += ( actionForm.year.value == '' )? 'rok' : '';
			notFilled += ( notFilled && ( actionForm.time.value=='' || actionForm.week_day.value=='' || actionForm.place.value=='' ) )? ', ' : '';
			notFilled += ( actionForm.time.value == '' )? 'čas' : '';
			notFilled += ( notFilled && ( actionForm.week_day.value=='' || actionForm.place.value=='' ) )? ', ' : '';
			notFilled += ( actionForm.time.value == '' )? 'den v týdnu' : '';
			notFilled += ( notFilled && actionForm.place.value=='' )? ', ' : '';
			notFilled += ( actionForm.time.value == '' )? 'místo konání' : '';
			window.alert(errorMessage+' (Nevyplněné pole: '+notFilled+')');
			return false;
		}
	else
		return true;
}
function IsValidMailForm( mailForm, errorMessage )
{
	if ( mailForm.email.value=='' || mailForm.message.value=='' || mailForm.email.value.indexOf('@')==-1 )
		{
			notFilled = ( mailForm.email.value == '' )? 'e-mail' : '';
			notFilled += ( notFilled && mailForm.message.value == '' )? ', ' : '';
			notFilled += ( mailForm.message.value == '' )? 'zpráva' : '';
			if ( mailForm.email.value != '' && mailForm.message.value != '' )
				notFilled = '';
			window.alert(errorMessage+' (Nevyplněné pole: '+notFilled+')');
			return false;
		}
	else
		return true;
}