2nd gen. apple tv and I tunes are set to show 1 photo album when playing my music. Why does apple tv quit showing my photos after just a few minutes and switch to the National Geographic photos? There are over 600 photos in the album I selected to

I have a 2nd generation Apple TV. I have set Home sharing on my computer to show 1 Photo album when I listen to music from my computer on Apple TV. I see that Photo album listed on my Apple TV. When I listen to music the Photo show will begin with the my designated Photo album. However, Apple TV will switch to the built in National Geographic photo file after about 5-10 mn. of music. There are over 600 photos in the Photo album I selected to use. Why is Apple TV automatically switching out of my Photo album?

Thanks,

Ellen