php - Insert correctly data with ajax for highcharts -

i have problem highchart. have put date database can't visualize correct graph. show full code , img of visualization have now. please me on that, i'm blocked 3 days in thing.

well js inizialize graph , call ajax function is:

$(function () {     var cs = document.getelementbyid('alunni').firstchild.nodevalue;       var rend = $('#alunni')      var options = {         chart: {             plotbackgroundcolor: null,                 plotborderwidth: null,                 plotshadow: false,                 renderto: rend[0]             },             title: {                 text: 'numero di studenti iscritti per ogni anno di corso'             },             tooltip: {                 pointformat: '{series.name}: <b>{point.percentage:.1f}%</b>'             },             plotoptions: {                 pie: {                     allowpointselect: true,                     cursor: 'pointer',                     datalabels: {                         enabled: true,                         color: '#000000',                         connectorcolor: '#000000',                         format: '<b>{point.name}</b>: {point.percentage:.1f} %'                     }                 }             },             series: [{                 type: 'pie',                 name: 'percentuale di alunni: ',             }]         };          $.ajax({             type: 'post',             url: 'alunnixclasse.php',             async: false,             data: {'cs': cs},             datatype: 'json',             success: function(data) {                 options.series[0].data = data;             },             error: function(data){                  alert("chiamata fallita, si prega di riprovare...");             }         });          console.log(options.series);          var chart = new highcharts.chart(options); }); 

and php use take date:

<?php      include "connect.php";      $codscu = $_post['cs'];      $query = "select * alunni alunni.codscu = $codscu ";     $query2 = "select total.totalun total total.codscu = $codscu ";      $risultato = mysql_query($query);     $risultato2 = mysql_query($query2);      $data = "";      $elem = mysql_fetch_array($risultato);     $tot = mysql_fetch_array($risultato2);      ($i = 0; $i <5; $i++) {         $anno = "";         switch($i) {             case 0: { $anno = "primo anno"; $value = ($elem['anno_1'] * 100) / $tot['totalun']; break; }             case 1: { $anno = "secondo anno"; $value = ($elem['anno_2'] * 100) / $tot['totalun']; break; }             case 2: { $anno = "terzo anno"; $value = ($elem['anno_3'] * 100) / $tot['totalun']; break; }             case 3: { $anno = "quarto anno"; $value = ($elem['anno_4'] * 100) / $tot['totalun']; break; }             case 4: { $anno = "quinto anno"; $value = ($elem['anno_5'] * 100) / $tot['totalun']; break; }         }          if ($i != 4) {             $data = $data."['".$anno."', ".number_format($value, 1,".","")."], ";         } else {             $data = $data."['".$anno."', ".number_format($value, 1,".","")."]";         }     }      print json_encode($data); ?> 

can me please... don't know error!