Paypal notify_url not working

I'm implementing paypal gateway in cakephp.I'm using following simple form. in Currently, it will accept the payment, and the payment gets processed ok,it just shows the standard PayPal 'Thank You' screen - there's no button to go back to my site, and it does开发者_如何学JAVAn't do it automatically.What I'd like to happen is for it to accept the payment, and then return to my site to say 'thank you' there;thanks

        <form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">
                <input type="hidden" name="notify_url" value="http://www.xxx.com/presult" />
                <input type="hidden" value="me@me.com" name="business">
                <input type="hidden" value="USD" name="currency_code">
                <input type="hidden" value="US" name="lc">
                <input type="hidden" value="test item" name="item_name">
                <input type="hidden" value="20.00" name="amount">
                <input type="hidden" value="1" name="test">
                <input type="hidden" value="http://xxx.com/posts/presult" name="return">
                <input type="hidden" value="paynow" name="type">
                <input type="hidden" value="_xclick" name="cmd">
                <input type="submit" value="Send" name="send">
            </form>

Typically the redirect is handled in 'manage' settings within the admin panel on the paypal site but you will not have this option available unless you pay for upgraded services. Paypal will allow you to register one url for redirect after authentication as well as a link for declined payment with an upgraded services package