Problem with mobile-only Ajax request

I have an Ajax code that takes data from a simple message field and sends it to my database without the page being updated, but the problem is that everything works perfectly just from the computer , when accessing the cell phone simply does not happen.

HTML

<form method="post" action="../controller/SendChatMessage.class.php?act=open_chat&id_unique_talk=<?=$get_id_unique_talk?>&to_id=<?=$get_id_para?>" id="send_message_chat" ajax="true">
      <div class="col-sm-10">
         <div class="message-area">
            <textarea placeholder="Message" rows="10" name="message" id="txt_message"></textarea>
         </div>
      </div>
      <button style="height:28px;margin-top:-39px !important;" type="submit" class="btn btn-primary pull-right"> <i class="fa fa-send"></i></button>
 </form>

JavaScript

<script type="text/javascript">
$(document).ready(function(e) {

  $("form[ajax=true]").submit(function(e) {

      e.preventDefault();

      var form_data = $(this).serialize();
      var form_url = $(this).attr("action");
      var form_method = $(this).attr("method").toUpperCase();

      $("#loading").show();

      $.ajax({
          url: form_url, 
          type: form_method,      
          data: form_data,     
          cache: false,
          success: function(returnhtml){                          
              $("#result").html(returnhtml); 
              $("#loading").hide();
              document.getElementById('txt_message').value='';
          }           
      });    

  });

});
</script>

Could anyone help me?