Re-test Additional Details
ok, I create a new site, new values etc and have isolated the problem.
It fails if your SQL query is expecting dynamic values. For instance, I don't expect to have a page for each product but rather use a $_GET to know what product I want to display data on.
for instance the query string in the page is ...product.php?id=1
Then the page converts that to a usable string value for SQL
<?php $pID = $_GET['id']; ?>
The the query is:
$query_rsinventory = "SELECT * FROM products WHERE products.ProductID = $pID";
In my latest test I used a static value and the dialog box worked as expected.
Hope this helps someone.