Erro ao efetuar busca em LDAP de dentro de um servlet

public void service(ServletRequest arg0, ServletResponse arg1)
			throws ServletException, IOException
	{
		connect();
	}
	
	public void connect()
	{
		try
		{
			Hashtable env = new Hashtable();
			
			env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
			env.put(Context.SECURITY_AUTHENTICATION, "simple");
			env.put(Context.SECURITY_PRINCIPAL, "cn=administrator,dc=..." );
			env.put(Context.SECURITY_CREDENTIALS, "...." );
			env.put(Context.PROVIDER_URL, "ldap://localhost:389/dc=...." );
			env.put("java.naming.ldap.version", "3");
			
			ctx = new InitialDirContext(env);
			
			if ( isObjectExist("dc", "...") )
			{
				System.out.println("dc=.... - exist");
			}
			else
			{
				System.out.println("dc=.... - not exist");
			}
		}
		catch (NamingException e)
		{
			e.printStackTrace();
		}		
	}
	
	public boolean isObjectExist(String obj, String value)
			throws NamingException
	{
		return search("",obj, value).hasMore();
	}

	public NamingEnumeration search(String bind, String att, String value)
			throws NamingException
	{
		return searchFull(bind, "(" + att + "=" + value + ")");
	}
	
	public NamingEnumeration searchFull(String bind, String filter)
			throws NamingException
	{
		SearchControls ctls = new SearchControls();
		ctls.setSearchScope( SearchControls.SUBTREE_SCOPE );
		
		NamingEnumeration result = ctx.search(bind, filter, ctls);
		
		return result;
	}