Problem: menu over images

Hi,
I purchased Hot Photo Gallery, already installed it, everything's fine, but I have a little problem that I can't work out: when I click on the thumbnails, the image box appears under the main orizontal menu, it's like the main menu overlaps the image.
I'm using Joomla 2.5.14, with Virtuemart installed, and an Artisteer template.

Thank you very much for helping!

p.s. I couldn't find an option to center the gallery in the page, it would be great if you could add this feature in the future.

Thanks again!

add this to bottom of template_css.css:

#jquery-lightbox{
z-index:99999;
}

Thank you so much, it works! There still remains a little problem though, (last question, I promise!) when I open the popup box, the menu bar becomes bright, isn't there a way to make it dark like the rest of the background? I attached a sreenshot.

Thank you again also for the quick support!

yes add also:

#jquery-overlay{
z-index:99998;
}