Some photos won't show in the video?? – VivaVideo - Video Editor&Maker Review

I was trying to make a video, I've actually been trying to make a few lately on my iPhone 5s, and some photos will not show up AT ALL in the slideshow. It'll go from one photo, once it switches the next photo will be a blank black one, and some other photos will do it too. Used to not have this problem and loved the app but now making videos on here is so hard when half of my photos won't even show up!!!
Review by MedicalGenius on VivaVideo - Video Editor&Maker.