address appears bug button buy code display documentation echo email fix info method order ourselves payer php post price product purchasers redirect searching snippet thank-you thank-you-page triggers txn usign website

I have been searching find any documentation on this. I want to redirect my purchasers to a thank you page on our website. Usign the GET method I want to be able to display their name, txn id etc. When I test this with a product with no price no info appears where it should.

A Snippet of the code on the thank you page looks like this

Thank you <?php echo $_GET['first_name']; ?><br>
<br>
Your order using the following email address <?php echo $_GET['payer_email']; ?> will now be

Any ideas what I might be doing wrong?

If you could, please post the Buy Now button code we provide for this test product; then we can test it ourselves and see what it triggers on our back end, just in case there's a bug we might need to fix.