Thanks for your troubleshooting on this. This is a weird issue since PowerGallery works and those first 3 steps are basically the same as for PowerStore.
What about if you make a page with these lines of code:
If the global.php has lines of code for error_reporting and ini_set, you can change those to look like this to give us full error reporting.
Also, have you tried just using Dreamweaver to create the connection and try and make a basic recordset?