PayPal return page problem

On payPal I added return page URL where user is redirected when payment is finished.

开发者_高级运维http://somewhere/back.aspx

But when I return from payPal after payment I don't get 'tx' or anything in queryString, what could be reason for that? I use correct token.

You cannot rely on the returnurl parameter for getting back any information about the PayPal transaction, those would be to easy to change.

You need to implement Instant Payment Notification (IPN) so you will get all the variables returned, here is an example : https://www.paypal.com/us/cgi-bin/webscr?cmd=p/pdn/ipn-codesamples-pop-outside