Ajax Failed Response to create a DataTable

I'm trying to build a json from an ajax query, and I try to put it in a Datatable and I get this error in the browser "DataTables warning: table id = example - Invalid JSON response. See http://datatables.net/tn/1 ", I do not know what I can do, help would help me a lot, thank you very much. I'm using Mongo as a database where I look for the relationship to get your id and send that id and get the detail and its attachment to arm the row of the table.

$(document).ready(function() {
    var jsonObj = [];
    $.ajax({
    type: "GET",
    url: "/obtenerRelacion",
    dataType: "json",
    success: function(relacion){
        for(var i in relacion) {
            var id = relacion[i].cajaChica._id;
            $.ajax({
                  type: "GET",
                  url: "/obtener/detalle/anexo/"+id+"",
                  dataType: "json",
                      success: function(cajaChica){
                        for(var j in cajaChica) {
                            item = {};
                            item['hechoPor'] = relacion[i].cajaChica.HECHO_POR_CORREO;
                            item['aprobadoPor'] = relacion[i].cajaChica.APROBADO;
                            item['categoria'] = cajaChica[j].NOMBRE_CATEGORIA;
                            item['valor'] = cajaChica[j].VALOR                          
                            item['ruc_ced'] = cajaChica[j].RUC_CED;
                            item['fecha'] = cajaChica[j].FECHA;
                            item['empresa'] = cajaChica[j].NOMBRE_EMPRESA;
                            item['entregadoA'] = cajaChica[j].NOMBRE_ENTREGADO;
                            item['proveedor'] = cajaChica[j].NOMBRE_PROVEEDOR;
                            item['cargadoA'] = cajaChica[j].NOMBRE_CARGADO;
                            item['detalle']= cajaChica[j].DETALLE_CAJA;
                            if(cajaChica[j].anexo != undefined){
                                item['tipo'] = cajaChica[j].anexo['TIPO'];
                                item['numFact'] = cajaChica[j].anexo['ESTAB_FAC']+''+cajaChica[j].anexo['PTO_FAC']+''+cajaChica[j].anexo['SEC_FAC'];
                            }else{
                                item['tipo'] = 'NO HAY';
                                item['numFact'] = 'NO EXISTE'
                            }
                            jsonObj.push(item);
                        }
                      }
                });
            }
    },
    complete: function(){
        $('#table').DataTable( {
                ajax: jsonObj,
            columns: [
                { title: "aprobadoPor" },
                { title: "cargadoA" },
                { title: "categoria" },
                { title: "detalle" },
                { title: "empresa" },
                { title: "entregadoA" },
                { title: "fecha" },
                { title: "hechoPor" },
                { title: "proveedor" },
                { title: "ruc_ced" },
                { title: "tipo" },
                { title: "valor" },
                { title: "numFact"}
            ]
          });
    }
  });
});

via Bakke Medina