dropzone post文件和数据

I have a problem when sending my files these last do not post

<div class="container"><form role="form" method="post" action="upload.php" class="dropzone" id="mydropzone" enctype="multipart/form-data">
<input type="hidden" name="additionaldata" value="1" /> 
<div class="form-group">
  <label  for="email">De</label>
  <input type="email" class="form-control "  name="email" placeholder="user@example.com" required />
  <span class="icon fa fa-envelope fa-lg"></span>
</div>
<div class="form-group">
  <label for="sub">Sujet</label>
  <input type="text" class="form-control "  name="sujet" placeholder="Sujet" required/>
  <span class="icon fa fa-pencil fa-lg"></span>
</div>
<div class="form-group">
  <textarea rows="5" cols="30"  name="msg" placeholder="Bonjour, insérer votre Message" style="width:100%"></textarea>
  <span class="icon-textarea fa fa-paper-plane fa-lg "></span>
</div>
<div class="dropzone-previews"></div>
<div><button id="submit-all" type="submit" class="btn btn default">Submit</button>
</div>
</form>

and my config dropzone

Dropzone.options.mydropzone = {        
        url: "upload.php" ,
        paramName: "file",
        previewsContainer: "#dropzone-previews", 
        autoProcessQueue: false,
        uploadMultiple: true, 
        addRemoveLinks:true,
        parallelUploads: 100,
        maxFiles: 100,
        acceptedFiles:".jpeg, .jpg, .jpe, .bmp, .png, .gif, .ico, .tiff, .tif, .svg, .svgz, 
\
                       .doc,.docx,.txt, .pdf,.rtf,.xlsx,.xls,.csv, .ppt,
\
                       .zip,.zipx,.tar,.gz,.z,.rar",
    init: function () {
    var submitButton = document.querySelector("#submit-all") 
    var myDropzone = this;

submitButton.addEventListener("click", function() {
myDropzone.processQueue(); 
});
this.on("sendingmultiple", function() {
});
this.on("successmultiple", function(files, response) {
     });
this.on("errormultiple", function(files, response) {
});
}
}

my upload.php for check post

<?php

if(!empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest') 
{
    echo "RECEIVED ON SERVER: 
";
    echo "FILES: 
";
    print_r($_FILES);
    echo "\$_POST: 
";
    print_r($_POST);
}

I am well directed to the page upload but this last remains blank nothing is send thank for your help

You need to access the response from the server in the successmultiple or errormultiple events:

As exemple, to display the response in the console:

this.on("successmultiple", function(files, response) {
    console.log(response);
});
this.on("errormultiple", function(files, response) {
    console.log(response);
});