'Buy Now' script & IPN.php Conflict?

[SteveStuartDJ]

My PaypalIPN.php has this line:

const VERIFY_URI = 'https://ipnpb.paypal.com/cgi-bin/webscr';

My Buy Now button has this line:
<form target="paypal" action="https://www.paypal.com/cgi-bin/webscr" method="post">

Is that correct with one going to ipnpb. and one going to www.paypal.com
Orders are scarce, there's something wrong somewhere, so I'm doing a process of elimintation, can anyone verify the above please?
If yours is working OK, can you take a look por favor?