Unable to get session data from paypal express checkout in laravel 4 - php

Question

I am unable to get session information in omnipay laravel 4 after getting express checkout return after making express checkout.
I do get Tokens and PayerID noting else. Session data of that site become empty.
Please tell how can I completePurchase Process. Is there any way to get purchase order ID from paypal. I am using omnipay.
public function doSaveAndProcessedToPayPal( $purchaseOrder)
{
$purchaseOrderId = $purchaseOrder->id;
Session::put('currentUserEmail', $email);
Session::put('purchaseOrderId', $purchaseOrderId);
Session::put('amount', $amount);
$gateway = $this->getPayPalGateway();
$items = new Omnipay\Common\ItemBag();
$items->add(array(
'name' => $productName,
'quantity' => '1',
'price' => (float)$amount,
));
$response = $gateway->purchase(
array(
'cancelUrl' => CANCEL_URL,
'returnUrl' => RETURN_URL,
'amount' => (float)$amount,
'currency' => $currency
)
)->setItems($items)->send();
$response->redirect();
}
public function doPerformPostPaymentOperation()
{
$gateway = $this->getPayPalGateway();
$purchaseOrderId = Session::get('purchaseOrderId');
$amount = Session::get('amount');
$currency = Session::get('currency');
$data = Session::all();
echo "<pre>";
print_r( $data );
echo "</pre>";
echo $purchaseOrderId;
die();
$response = $gateway->completePurchase(array(
'transactionId' => "ORD-".$purchaseOrderId,
'transactionReference' => "REF-".$purchaseOrderId,
'amount' => (float)$amount,
'currency' => $currency,
))->send();
if ( ! $response->isSuccessful())
{
throw new Exception($response->getMessage());
}
}
Output
Array
(
[_token] => lnvG1S3eU2JsHJSciOTjixEEHiSwZVX47daRLDXE
[flash] => Array
(
[old] => Array
(
)
[new] => Array
(
)
)
)