function mostrarCaja(num,zona) { 

	//alert(num);

	if(window.XMLHttpRequest) {
		objXml = new XMLHttpRequest(); // Gecko (Firefox, Moz), KHTML (Konqueror, Safari), Opera
	} else if(window.ActiveXObject) {
		objXml = new ActiveXObject("Microsoft.XMLHTTP"); // Internet Explorer		
	}					
	
	objXml.open("GET", "carga.asp?id="+num+"&zona="+zona, true);
	
	objXml.onreadystatechange=function() {
   		if (objXml.readyState==4) {       			
   			document.getElementById('caja_selec').innerHTML=objXml.responseText; 
 		}   
	}

	objXml.send(null);	

	//document.getElementById('caja_selec').style.visibility = 'visible'

	if (document.getElementById('caja_selec').style.visibility == 'visible') {
	
		document.getElementById('caja_selec').style.visibility = 'hidden';


	}else{
		document.getElementById('caja_selec').style.visibility = 'visible';
		
	}	
	

					
}