200 Error on second Ajax request

Question

I am creating a custom module. And I'm having trouble with ajax. I've looked for the answer haven't found anyone with a similar problem.

What's supposed to happen:

Insert a date on the textfield. Click the button and the data below will change depending on the date. Data is stored on json files.

What's the problem:

Only the first request works. From the second request on it gives an error code 200 with an empty response.

What I've tested

I have tested with a simpler ajax where I get a specific data from a file and output the data on a div. It stops working when I use the "page" element.

Here's my code:

$form['dates'] = array(
    '#type'=>'textfield',
    '#title'=>'Choose the date',
    '#id'=>'datepicker',
    '#default_value'=>$selected,
);

$form ['submit'] = array (
            '#type' => 'submit',
            '#ajax' => array (
                    'callback' => 'freports_alunos_dados_callback',
                    'wrapper' => 'dados_content_wrapper',
                    'effect' =>'fade',
            )
            ,
            '#value' => t ( 'Ver Dados' ) 
    );

    $form['page'] = array(
            '#theme' => 'freports_alunos_tpl',
            '#type' => 'markup',
            '#prefix' => '<div id="dados_content_wrapper">',
            '#suffix' =>'</div>',
            '#dados' => freports_get_dados($selected),
    );



function freports_alunos_dados_callback($form, &$form_state){
    $element = $form['page']; // << FROM MY TESTS THE PROBLEM STARTS HERE
    $element['#dados'] = freports_get_dados($form_state['values']['datas']);
    return $element;
}

function freports_theme($existing, $type, $theme, $path) {
    return array (
            'freports_alunos_tpl' => array (
                    'variables' => array (
                            'dados' => NULL 
                    ),
                    'template' => 'tpl/alunos' 
            ),
            'freports_curso_alunos_tpl' => array (
                    'variables' => array (
                            'dados' => NULL,
                            'filial' => NULL,
                            'curso' => NULL 
                    ),
                    'template' => 'tpl/curso_alunos' 
            ),
            'freports_turma_alunos_tpl' => array (
                    'variables' => array (
                            'dados' => NULL,
                            'filial' => NULL,
                            'curso' => NULL,
                            'turma' => NULL 
                    ),
                    'template' => 'tpl/turma_alunos' 
            ) 
    );
}

Page TPL:

<?php 
drupal_add_js(drupal_get_path('module','freports').'/js/freports.js','file'); 
?>

<div>
<!-- <strong>Escolher Data: </strong><input type="text" id="datepicker"><button onclick="getData(document.getElementById('datepicker').value)">Go</button><br /> -->
<strong>Atualizado em: </strong><?php print $dados->updated ?><br /><br />
<strong>Total Alunos: </strong><?php print $dados->totalAlunos;?><br />
<strong>Total Gama: </strong><?php print $dados->filial[0]->totalAlunos; ?><br />
<strong>Total Lago: </strong><?php print $dados->filial[1]->totalAlunos; ?><br />
<br /><br />

<table>
    <tr ALIGN=center>
        <td COLSPAN="2"><strong> CAMPUS - GAMA </strong></td>
    </tr>
    <tr>
        <td><strong>Curso</strong></td>
        <td><strong>Total Alunos<strong></td>
    </tr>
<?php $i=0; foreach($dados->filial[0]->cursos as $cursos_gama){ ?>
    <tr style="border-bottom:1px solid black;">
        <td><a href="<?php print 'alunos/filial/0/curso/'.$i ?>"><?php print $cursos_gama->nome; ?></a></td>
        <td style="text-align:right;"><?php print $cursos_gama->totalAlunos; ?></td>
    </tr>
<?php $i++;} ?>
</table>
<br /><br />
<table>
    <tr ALIGN=center>
        <td COLSPAN="2"><strong> CAMPUS - LAGO </strong></td>
    </tr>
    <tr>
        <td><strong>Curso</strong></td>
        <td><strong>Total Alunos<strong></td>
    </tr>
<?php $i=0; foreach($dados->filial[1]->cursos as $cursos_lago){ ?>
    <tr style="border-bottom:1px solid black;">
        <td><a href="<?php print 'alunos/filial/1/curso/'.$i ?>"><?php print $cursos_lago->nome; ?></a></td>
        <td style="text-align:right;"><?php print $cursos_lago->totalAlunos; ?></td>
    </tr>
<?php $i++;} ?>
</table>

Answer 1

I solved my problem.

I didn't close the <div> while testing the .tpl.php page file.