Problems with posting Paypal values - php

Question

It is assumed that using the form, variables are passed by post method to return page, but it is not doing that, and I don't know what I can do about it, since transit through the Paypal website is out of my control.
Any idea?
This is my button. I have the same situation with another one.
<form name="_xclick" action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post" target="_top">
<input type="hidden" name="cmd" value="_xclick">
<input type="hidden" name="business" value="name#dom.com">
<input type="hidden" name="currency_code" value="EUR">
<input type="hidden" name="item_name" value="Algo">
<input type="hidden" name="amount" value="8.00">
<input type="hidden" name="no_shipping" value="1">
<input type="hidden" name="item_number" value="<?php echo $_GET['id'];?>">
<input type="hidden" name="custom" value="<?php echo $_GET['sub'];?>">
<input type="hidden" name="return" value="http://www.web.com/ok.php">
<input type="hidden" name="cancel_return" value="http://www.web.com/ko.php">
<input type="image" src="http://www.paypal.com/img/btn_buynow_LG.gif" border="0" name="submit" alt="Make payments with PayPal">
</form>

Answer 1

You can pass the variables by setting them as url parameters in the return page. Like this:
<input type="hidden" name="return" value="http://www.web.com/ok.php?id=<?php echo $_GET['id'];?>&custom=<?php echo $_GET['sub'];?>">