IPN is getting INVALID in LIVE box, but working good with Sandbox

[kjsunilkj]

IPN is getting INVALID in LIVE box, but working good with Sandbox. Please do help me to identify the issue here

---------------------------------------POST Response----------------------------------------------------------------------------------------------------------

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[12/05/2016 12:31 PM] - https://www.paypal.com/cgi-bin/webscr (curl)
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HTTP/1.1 200 OK
Server: Apache
X-Frame-Options: SAMEORIGIN
Cache-Control: max-age=0, no-cache, no-store, must-revalidate
Pragma: no-cache
HTTP_X_PP_AZ_LOCATOR: slcb.slc
Paypal-Debug-Id: 121ce9f69f66d
Cache-Control: max-age=0, no-cache, no-store, must-revalidate
Pragma: no-cache
Content-Type: text/html; charset=UTF-8
DC: ccg11-origin-www-2.paypal.com
Date: Mon, 05 Dec 2016 07:01:45 GMT
Content-Length: 7
Connection: close
Set-Cookie: cwrClyrK4LoCV1fydGbAxiNL6iG=bf5bwUgrcWamn6k91U1NUAZkA3NGCG1wZxs0jc6q_AhpBWaQoM-CqFFtscvkqNvLj65gO-soqQDt8ga0U5Vysj_EdYEl26gt0p9ciReayVHdUryazEtEqjhv1hD8pgVsMlxvhFP1pQ5ZoOtWS_nwvGJH9nQjxOQA1IPwED-iLtOtXOVUFf8z6lyIMN3mM8Sw3tDCN5EQ7-DqBJZ1pcm621hrA4lz9L_s9YvROxRNnnZHRSKb_NVr7qs5dFc0-ZOu5qNtOC18HMPHD9EHowtBe2GqHN8EQr00Djv3pv7pJVWQdv3ABAJ6Rxd6ph4ZghZV2vIlj1IL2ifMOPX91CbH7dHCpw2LFHabIdtOFuMjsZ7yaaX7l8PL4Ey6_bI5AHPmPR8Uu9_P1DSAZ6VRCQveLyRDQgGV3Y2i4BrwQ-7UVYAEkXRz48VlzIV6ZBK; domain=.paypal.com; path=/; Secure; HttpOnly
Set-Cookie: cookie_check=yes; expires=Thu, 03-Dec-2026 07:01:44 GMT; domain=.paypal.com; path=/; Secure; HttpOnly
Set-Cookie: navcmd=_notify-validate; domain=.paypal.com; path=/; Secure; HttpOnly
Set-Cookie: navlns=0.0; expires=Wed, 05-Dec-2018 07:01:44 GMT; domain=.paypal.com; path=/; Secure; HttpOnly
Set-Cookie: X-PP-SILOVER=name%3DLIVE5.WEB.1%26silo_version%3D880%26app%3Dappdispatcher%26TIME%3D3624944984%26HTTP_X_PP_AZ_LOCATOR%3Dslcb.slc; Expires=Mon, 05 Dec 2016 07:31:45 GMT; domain=.paypal.com; path=/; Secure; HttpOnly
Set-Cookie: X-PP-SILOVER=; Expires=Thu, 01 Jan 1970 00:00:01 GMT
Set-Cookie: AKDC=ccg11-origin-www-2.paypal.com; expires=Mon, 05-Dec-2016 07:31:45 GMT; path=/; secure
Set-Cookie: akavpau_ppsd=1480921905~id=9013a9da138d7db2cc2294221d985852; path=/
Strict-Transport-Security: max-age=63072000

INVALID
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txn_id 3MJ6733400603303W
mc_currency USD
mc_fee 0.70
mc_gross 9.00
protection_eligibility ELIGIBLE
payment_date 2016-12-05T07:01:32Z
payment_fee 0.70
payment_gross 9.00
payment_status Completed
payment_type INSTANT_TRANSFER
business ESLK5VUUMC9X4
receiver_id ESLK5VUUMC9X4
payer_email kadsfdsran.vindsfsdfayadfk@gmfdsfail.com
payer_id VUF4U6G8UYJP8
payer_status VERIFIED
first_name dfdsf
last_name sdfsdfs
address_name dfdfsf
address_street 45453stredfdfet
address_city dfddfsd
address_state Tasmania
address_country_code AU
address_zip 454543
residence_country AU
item_name Online OQA
item_number P000000123445270
quantity 1
charset windows-1252

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Respective code snippet, Here the below code is throwing false and returnign invalid IPN,

elseif (strpos($this->response, "INVALID") !== false) {
return false;

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public function processIpn($post_data=null) {

$encoded_data = 'cmd=_notify-validate';

if ($post_data === null) {
// use raw POST data
if (!empty($_POST)) {
$this->post_data = $_POST;
$encoded_data .= '&'.file_get_contents('php://input');
} else {
throw new Exception("No POST data found.");
}
} else {
// use provided data array
$this->post_data = $post_data;

foreach ($this->post_data as $key => $value) {
$encoded_data .= "&$key=".urlencode($value);
}
}

if ($this->use_curl) $this->curlPost($encoded_data);
else $this->fsockPost($encoded_data);

if (strpos($this->response_status, '200') === false) {
throw new Exception("Invalid response status: ".$this->response_status);
}

if (strpos($this->response, "VERIFIED") !== false) {
return true;
} elseif (strpos($this->response, "INVALID") !== false) {
return false;
} else {
throw new Exception("Unexpected response from PayPal.");
}
}