php json_decode is not working Properly - php

Question

When i am Decoding using commented "$jsonString" String it is working very well.
But after using curl it is not working, showing Null.
Please Help Me in this.
if (isset($_POST['dkno'])) {
$dcktNo = $_POST['dkno'];
$url = 'http://ExampleStatus.php?dkno=' . $dcktNo;
$myvars = '';
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $myvars);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$jsonString = curl_exec($ch);
// $jsonString = '[{"branchname":"BHUBNESHWAR","consignee":"ICICI BANK LTD","currentstatus":"Delivered by : BHUBNESHWAR On - 25/07/2015 01:00","dlyflag":"Y","PODuploaded":"Not Uploaded"}]';
if ($jsonString != '') {
$json = str_replace(array('[', ']'), '', $jsonString);
echo $json;
$obj = json_decode($json);
if (is_null($obj)) {
die("<br/>Invalid JSON, don't need to keep on working on it");
} else {
$podStatus = $obj->PODuploaded;
}
}
}
}

Answer 1

After curl I used following concept to get only JSON data from HTML Page.
1) fetchData.php
$url = 'http://DocketStatusApp.aspx?dkno=' . $dcktNo;
$myvars = '';
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $myvars);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$jsonString = curl_exec($ch);
// now get only value
$dom = new DOMDocument();
$dom->loadHTML($jsonString);
$thediv = $dom->getElementById('Label1');
echo $thediv->textContent;
2) JSONprocess.php
if (isset($_POST['dkno'])) {
$dcktNo = $_POST['dkno'];
ob_start(); // begin collecting output
include_once 'fetchData.php';
$result = ob_get_clean(); // Completed collecting output
// Now it will show & take only JSON Data from Div Tag
$json = str_replace(array('[', ']'), '', $result);
$obj = json_decode($json);
if (is_null($obj)) {
die("<br/>Invalid JSON, don't need to keep on working on it");
} else {
$podStatus = $obj->PODuploaded;
}
}