Please do not refer me to the "how to edit a gallery" link, as I have already tried those instructions :-\  Please help.

I have read the instructions under 'Edit a Gallery' in the SimpleViewer instruction guide, but this method does *not* work (or no longer works...???). 

Please help.  I have a gallery with 23 photos built (and it looks terrific), more photos need to be added. Using WP 3.5.1

Part of the how-to instructions say: 
◦ Click the 'Add Media' button. Click the 'Gallery' tab to view, delete and re-order images. Click 'From Computer' to add new images.

The problem: 
Once I click the 'Add Media' button (on the page), there is no 'Gallery' tab to view.  Is this due to update of WP?  Is SimpleViewer no longer working on WP (3x)?

As for these instructions, once the 'Add Media' button is selected the only choices are to: Upload Files, Media Library, Create Gallery, Set Featured Image.
There is no 'Gallery' tab to select from.  Please help as I really need to add more photos.

Thank you!