Ajax函数出了什么问题

Question

I've copied the ajax function from another page, but it's not working in this page, it's exactly the same in both pages. O put 2 alerts (STEP1 and STEP2) but only the STEP1 is activated, the STEP2 doesn't appear. Any ideia? Thanks

The Ajax function is

function DadosGerais(){
  alert("STEP1");
  $.ajax({
  url: "php/c_consultas.php?tipo_acao=consulta_detalhes_consulta&id_consulta="+getUrlVars()['id_consulta'],
  type: 'post',
  data: { tag: 'getData'},
  dataType: 'json',
  success: function (data) {
  alert("STEP2");
  if (data.success) {
    $.each(data, function (index, record) {                         
    if ($.isNumeric(index)) { 
      $('#cliente').val(record.cliente_nome).show();
      $('#contacto').val(record.nome_contacto).show()
    }
  });
  }
},
  error: function (XMLHttpRequest, textStatus, errorThrown) { 
    alert("Status: " + textStatus);
    alert("Error: " + errorThrown);
  }
  });       
}

If I call the 'url' directly in the browser it returns me the json data (it's ok). Maybe it's missing some JQuery file????