marketpress more images for product


Im looking to resolve the following:

When Adding a 'Featured Image' I dont seem to be able to add an image-gallery?
Actually I can, but (when viewing the product and) when clicking the Featured Image picture, the lightboxpop-up does not include the gallery images? Just showing 1/1 pictures

in return, when clicking the gallery images it DOES include the featured image. 3/4 (3 Galley images included).

One could think:
Just don't add a Featured Image?
But .... thenit shows a 'no-picture-symbol' when viewing all products in a grid ....

So ... any advice how to escape this (cull de sac)?