dropzone $_FILES is empty - php

Question

I try to submit a form with some dropzone-added files and additional fields.
I don´t want those dropzone Ajax Features, because i want to add some information by additional inputs.
So, at least a very simple Submit-Form with multiple Files, which gets processed after pressing the submit button.
So far, the client side works fine, but when I submit the form, $_FILES is empty! Why?
What I got so far:
<?
if(isset($_POST))
{
print_r($_POST);
print_r($_FILES);
exit;
}
?>
<form id="smart-form" enctype="multipart/form-data" method="POST" action="upload.php">
<div class="form-body">
<div class="section">
<div class="dropzone" id="myDropzone">
<h3 class="dz-drop-title"> Drop files here or </h3>
<p class="dz-clicker"> <span> Browse File </span> </p>
<div class="fallback">
<input name="file[]" type="file" multiple />
</div>
</div>
</div><!-- end section -->
</div><!-- end .form-body section -->
<label style="padding: 5px;" for="another_field_1">another field 1 <input id="another_field_1" type="text" name="testinput1"></label><br>
<label style="padding: 5px;" for="another_field_2">another field 2 <input id="another_field_2" type="text" name="testinput2"></label>
<div class="form-footer">
<button type="submit" class="button btn-primary"> Send Form </button>
</div><!-- end .form-footer section -->
</form>
<script type="text/javascript">
jQuery(document).ready(function($){
jQuery(".dropzone").dropzone({
url: "upload.php",
dictDefaultMessage: "Datei bitte hier ablegen!",
success: function() {
jQuery('.success-mark').show();
jQuery('.error-mark').hide();
},
error: function() {
jQuery('.success-mark').hide();
jQuery('.error-mark').show();
}
});
});
</script>