function checkfields() {

	var lang = document.getElementById('lang').value;

	if(lang == 'en') {		
		if(!document.getElementById('calInput1').value) {
			alert('Please, be sure that field "Start Date" has a correct value.');
			return false;
		} else {
			var boundInt = parseInt(document.getElementById('BoundProduct').value);
			if (isNaN(boundInt) || boundInt < 0) {
	            alert('Please, be sure that field "Package Type" has a correct value.');
				return false;
	      	}
	      	document.getElementById('BoundProduct').value = boundInt;
			document.form_busqueda.submit();
		}
	} else {
		if(!document.getElementById('calInput1').value) {
			alert('Por favor, aseg\u00FArese de que el campo "Fecha entrada" tienen valor.');
			return false;
		} else {
			var boundInt = parseInt(document.getElementById('BoundProduct').value);
			if (isNaN(boundInt) || boundInt < 0) {
	            alert('Por favor, aseg\u00FArese de que el campo "Tipo paquete" tienen un valor correcto.');
				return false;
	      	}
	      	document.getElementById('BoundProduct').value = boundInt;
			document.form_busqueda.submit();
		}
	}
}