problem using ecart with framework builder

I am putting together a store and trying to use framework builder and plugins.

I created a few vanilla pages with no css, which work in their own right, and am now trying to use these pages as plugins.

Having a problem with my productdetails page, which incorporates my add to cart form.
It works fine , so I copied the page to my plugins folder
When I try and use the page from the plugins folder, ie siteroot/plugins/productdetails.php, the page loads ok, but nothing happens when I click the add to cart button,

when I use the page created with the productdetails plugin, on clicking the add to cart button, I get an error message...
You don't have permission to access /plugins/Notice: Undefined index: ../PHP_SELF in /plugins/productdetails.php on line 349 on this server.

This is the form action created automatically using ecart 5, how can I fix this ?

Ok, I fixed it.

When I moved the page to the plugins folder, I updated the links, so that the form action was changed from
<?php echo $_SERVER["PHP_SELF"]; ?>
to
<?php echo $_SERVER[".../PHP_SELF"]; ?>

corrected the path and it works again!

;-)