var ajax3 = new sack();		
	
		function UserCheck(){
			 var username=document.getElementById('signup_username').value   
	     if (username.length > 2 ) {
	     ajax3.requestFile =  'ajax_checkusername.asp?username=' + username;
	     ajax3.onCompletion = handleResponse;
	     ajax3.runAJAX(); 
	    } else {
	    	document.getElementById('TakenOrNot').innerHTML = '*Minimaal 3 tekens.<Br>Gebruik alleen letters, cijfers en het teken: _';
	    }
	  }

	  function handleResponse()	{
			document.getElementById('TakenOrNot').innerHTML = ajax3.response;
	  }