oscommerce allow running script independently on different folder

Question

I have oscommerce installed on a domain (www.myoscommercesite.com), but now i want to run an independent script (www.myoscommercesite.com/myindependentscript) but getting a 404 message

I have tried adding this into htaccess file

<FilesMatch "\.(php)$">
Order Deny,Allow
    Allow from all
</FilesMatch>

But problem still there

Thanks