How to Insert Data to Mysql Database using Volley

I am trying to insert data to mysql database using volley, but it always response as error, I'm stuck and cant go further to my project. I can't find what causing it not to execute the my PHP codes. I also checked my PHP code using PostMan and it is working well. I'm now trying to insert some test data to it but still no luck. I hope you can shine some light in me and provide me some help. Thank you.

Insert.Java

Button confirmOrder = (Button) findViewById(R.id.confirmOrder); confirmOrder.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { final int a = 1; final String b = "Beth"; final int c = 1; final int d = 3; final int e = 1; final String f = "Bert"; final String URL = "https://10.0.2.2/myDB/order.php"; StringRequest stringRequest = new StringRequest(Request.Method.POST, URL, new Response.Listener<String>() { @Override public void onResponse(String response) { if(response.contains("success")) { Toast.makeText(getApplicationContext(), "success", Toast.LENGTH_SHORT).show(); } } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { Toast.makeText(getApplicationContext(),"failed",Toast.LENGTH_SHORT).show(); } }){ @Override protected Map<String, String> getParams() throws AuthFailureError { Map<String, String> params = new HashMap<>(); params.put("table_id", String.valueOf(a)); params.put("cust_name", b); params.put("item_id", String.valueOf(c)); params.put("quantity", String.valueOf(d)); params.put("status_id", String.valueOf(e)); params.put("username", f); return params; } }; MySingleton.getInstance(getApplicationContext()).addToRequestQueue(stringRequest); } }); 

order.php

<?php include_once("init.php"); if(isset($_POST['table_id']) && isset($_POST['cust_name']) && isset($_POST['item_id']) && isset($_POST['quantity']) && isset($_POST['status_id']) && isset($_POST['username'])){ $tableid = $_POST['table_id']; $custname = $_POST['cust_name']; $itemid = $_POST['item_id']; $quantity = $_POST['quantity']; $statusid = $_POST['status_id']; $username = $_POST['username']; $query = "INSERT INTO tbl_order(table_id,cust_name,item_id,quantity,status_id,username) VALUES ('$tableid', '$custname', '$itemid', '$quantity', '$statusid', '$username')"; $result = mysqli_query($con, $query); if($result > 0){ echo "success"; } else{ echo "failed"; } } ?>