When Magento has the third-party theme which modifies the gallery (overwrites product.info.media section), it's necessary to replace:

<block type="catalog/product_view_media" name="product.info.media" as="media" template="catalog/product/view/media.phtml">

with

<block type="catalog/product_view_media" name="product.info.media" as="media" template="orbitvu_sunn/product/view/gallery.phtml">