title: ReturnURL for Paypal Adaptive Payments
body: <p>I'm trying to use AdaptivePayments to send funds from one user to another user via my site, so I can check whether or not they've actually gone through with the payment. The payment goes through, but they're not returned to my site so I can't track the payment.</p>
  
  <p>I'm redirecting to `https://www.sandbox.paypal.com/webscr&amp;cmd=_ap-payment&amp;paykey=MYKEY
  But I jsut get takn to 'My Account' and see the payment is successful, but not redirected.</p>
  
  <p>I've also tried redirecting to <code>https://sandbox.paypal.com/webapps/adaptivepayment/flow/pay?&amp;paykey=MYKEY</code> but I get:</p>
  
  <blockquote>
    <p>This transaction has already been approved. Please visit your PayPal
    Account Overview to see the details.</p>
  </blockquote>
  
  <p>I'm redirecting by setting is <code>NVPRequest["returnUrl"] = "http://mysite.com/APReturn.aspx</code> but this is seemingly ignored. Is there a way to do this or a better method of achieving what I need?</p>