为什么我得到这个错误值成功的java.lang.string类型无法转换为JSONOBJECT？

I am developing this android app which I send the data on server and then I have to retrieve the data and show them on a chart (anychartLibrary).

I've written this php code which helps me send the date to the server and retrieve the data related to that date, but instead of getting a jsonObject I get this html line, which I have noticed using Postman...

<?php
if ($_SERVER['REQUEST_METHOD']=='POST') {

    require_once('init.php');

    $myDate =$_GET['myDate'];

    $sql =" SELECT * FROM parkinsonism_value WHERE myDate='$myDate' ;";
    $result = mysqli_query($connect,$sql);

    $row = mysqli_fetch_assoc($result);

    if (isset($row)) {       
        $record['myDate'] = $row['myDate'];
        $record['parkinsonism'] = $row['parkinsonism'];            
    } else {
        $record['myDate'] ="";
        $record['parkinsonism'] ="";
    }

    header('Content-type=application/json');
    echo json_encode(array("list"=>$record),JSON_UNESCAPED_SLASHES);      
}
?>

and this is the volley json Object Request:

public void getString(){
    String url = "http://46.4.151.237/StHans/getparkinsonism.php"+"?myDate="+finalDate;

    JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.POST, url, null, new Response.Listener<JSONObject>() {

    @Override
    public void onResponse(JSONObject response) {

        Toast.makeText(getContext(),response.toString(),Toast.LENGTH_SHORT).show();
            try {
                 jsObject =response.getJSONObject("list");
                 sss =jsObject.getString("parkinsonism");
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Toast.makeText(getContext(),error.getMessage(),Toast.LENGTH_SHORT).show();
        }
    });

    // Access the RequestQueue through your singleton class.
    MySingleton.getInstance(getContext()).addToRequestQueue(jsonObjectRequest);
}

by the way about the final date:

calendar = Calendar.getInstance();
year = calendar.get(Calendar.YEAR);
month = calendar.get(Calendar.MONTH);
dayOfMonth = calendar.get(Calendar.DAY_OF_MONTH);

finalDate =dayOfMonth +"/"+(month +1)+"/"+ year;

now I have this error which tells me value success of type java.lang.string cannot be converted to JSONOBJECT. what should I change to get this to work? thanks:|