Lightbox default template won't serve through DFP

[bc...@bangordailynews.com]

I am new to GWD and have been trying to make a lightbox HTML5 ad display on our website via DFP. The preview from GWD will function correctly, and I publish as a .zip and upload into DFP as HTML5 with no errors, but when I preview the creative I get an empty white space where the ad is trying to serve but nothing shows up. Am I missing an important step? Thanks