PHP - No aparece select en autocomplete

<select name="categoria">

    <option value="smartphone">Smartphone</option>

    <option value="tablet">Tablets</option>

    <option value="monitor">Monitores</option>

    <option value="camara">Cámaras digitales</option>

    <option value="almacenamiento">Almacenamiento</option>

</select>

<?php

    if (isset($con))

    {

?>

<div class="modal fade" id="nuevocontrato" tabindex="-1" role="dialog" data-backdrop="static"  aria-labelledby="myModalLabel">

  <div class="modal-dialog" role="document">

    <div class="modal-content">

      <div class="modal-header vent">

        <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>

        <h4 class="modal-title" id="myModalLabel"><i class='glyphicon glyphicon-edit'></i> Agregar nuevo contrato</h4>

      </div>

    <div class="modal-body">

        <form class="form-horizontal" method="post" id="guardar_contrato" name="guardar_contrato">

        <div id="resultados_ajax_empleado"></div>

          <div class="form-group">

            <label for="nombre" class="letras col-sm-2 control-label">Primer Nombre</label>

                <div class="col-sm-4">

                    <input type="text" class="form-control caja" id="nombre" name="nombre" required >

                </div>

                <label for="apellido_emple1" class="letras col-sm-2 control-label">Apellido</label>

                <div class="col-sm-4">

                    <input type="text" class="form-control caja" id="apellido_paterno" name="apellido_paterno" readonly>

                </div>

          </div>

          <label for="estado" class="letras col-sm-2 control-label">Cargo</label>

                    <div class="col-sm-4">

                        <select class="form-control caja" id="id_cargo" name="id_cargo" required="tiene que buscar un empleado" onchange="mostrarsueldo()">

                             <?php

                                $sql_producto=mysqli_query($con,"select * from cargo order by nombre_carg");

                                    while ($rw=mysqli_fetch_array($sql_producto)){

                                        $id_cargo=$rw["id_cargo"];

                                        $nombre=$rw["nombre_carg"];

                                        if ($id_cargo==$_SESSION['id_cargo']){

                                            $selected="selected";

                                        } else {

                                            $selected="";

                                        }

                                        ?>

                                        <option value="<?php echo $id_cargo?>" <?php echo $selected;?>><?php echo $nombre?></option>

                                        <?php

                                    }

                                            ?>

                        </select>

                    </div>

            <div class="form-group">

                <label for="cedula" class="letras col-sm-2 control-label">Cedula:</label>

                    <div class="col-sm-4">

                        <input type="text" class="form-control caja" id="cedula" name="cedula" readonly>

                        <input type="hidden" id="id_empleado" name="id_empleado" >

                    </div>

            </div>

            <div class="form-group">

                <label for="fecha_ingreso" class="letras col-sm-2 control-label">Inicio Contrato</label>

                <div class="col-sm-4">

                    <input type="text" class="form-control caja" id="fecha_ingreso" name="fecha_ingreso" autocomplete="off">

                </div>

                <label for="datepicker" class="letras col-sm-2 control-label">Fin Contrato</label>

                <div class="col-sm-4">

                    <input type="text" class="form-control caja" id="datepicker" name="datepicker" autocomplete="off" placeholder="Seleccione la fecha" required="Tiene que elegir fecha">

                </div>

            </div>

    </div>

      <div class="modal-footer">

        <button type="button" class="btn btn-default"data-dismiss="modal">Cerrar</button>

        <button type="submit" class="btn_slider btn btn-primary" id="guardar_datos">Guardar datos</button>

      </div>

      </form>

    </div>

  </div>

</div>

<?php

    }

?>

/*********	 autocomplete        ********************/

$(function() {

    $("#nombre").autocomplete({

        source: "./ajax/autocomplete/empleado.php",

        minLength: 2,

        select: function(event, ui) {

            event.preventDefault();

            $('#id_empleado').val(ui.item.id_empleado);

            $('#nombre').val(ui.item.nombre);

            $('#cedula').val(ui.item.cedula);

            $('#apellido_paterno').val(ui.item.apellido_paterno);

         }

    });

});

$("#nombre" ).on( "keydown", function( event ) {

    if (event.keyCode== $.ui.keyCode.LEFT || event.keyCode== $.ui.keyCode.RIGHT || event.keyCode== $.ui.keyCode.UP || event.keyCode== $.ui.keyCode.DOWN || event.keyCode== $.ui.keyCode.DELETE || event.keyCode== $.ui.keyCode.BACKSPACE )

    {

        $("#id_empleado" ).val("");

        $("#cedula" ).val("");

        $("#apellido_paterno" ).val("");

    }

    if (event.keyCode==$.ui.keyCode.DELETE){

        $("#apellido_paterno" ).val("");

        $("#nombre" ).val("");

        $("#id_empleado" ).val("");

        $("#cedula" ).val("");

    }

});

/*********fin de	 autocomplete        ********************/

<?php

if (isset($_GET['term'])){

include("../../config/db.php");

include("../../config/conexion.php");

$return_arr = array();

if ($con)

{

    $fetch = mysqli_query($con,"SELECT * FROM empleados where nombre like '%" . mysqli_real_escape_string($con,($_GET['term'])) . "%' LIMIT 0 ,50");

    while ($row = mysqli_fetch_array($fetch)) {

        $id_empleado=$row['id_empleado'];

        $row_array['value'] = $row['nombre'];

        $row_array['id_empleado']=$id_empleado;

        $row_array['nombre']=$row['nombre'];

        $row_array['apellido_paterno']=$row['apellido_paterno'];

        $row_array['cedula']=$row['cedula'];

        array_push($return_arr,$row_array);

    }

}

mysqli_close($con);

echo json_encode($return_arr);

}

?>