Subscription doesn't return transaction details.

[Gayan]

I'm a PHP developer 

I'm using PayPal for a subscription using a query string. Following is the query string which I have used 

$quary_string="https://www.paypal.com/cgi-bin/webscr

&cmd=_xclick-subscriptions

&business=

&undefined_quantity=1

&item_name=Freedom Travel 4 You Registration

&amount=".$signup_price."

&currency_code=USD

&lc=US

&bn=PP-SubscriptionsBF

&rm=2

&a1=".$signup_price."

&p1=1&t1=M

&a3=".$monthly_fee."

&p3=1

&t3=M

&src=1

&sra=1

&no_note=1 

&custom=".$this->data['User']['reference_id']."

&cbt=Complete Subscription

&notify_url=http://ts-v2.dev.laknipayum.com/signup/ipn_update

&return=http://ts-v2.dev.laknipayum.com/signup/ipn_update

&cancel_return=http://ts-v2.dev.laknipayum.com/signup/home";

I'm using PayPal IPN and I have used the same return url in IPN settings and the IPN is enabled.

with the query string I have successfully completed the subscription in both Sandbox.

My question is, when I use PayPal.com after returning to the return URL I'm not getting any of the transaction details to the $_POST variable. 

But when I use the sandbox I'm receiving all the required subscription details to the $_POST variable.

Please let me know If I have done anything wrong in the query string or anything I need to setup in PayPal merchant account. Even though I successfully complete the PayPal payment since I didnt receive the transaction details I couldnt been able to update the paypal payment tables in the server. 

I really  need this to be rectified as soon as possible.

Thank you