White border surrounding InDesign pages sent to iPhoto

Since Apple stopped its iPhoto book service several years ago, I have continued making them, sending PDFs to Mimeo for successful printing. In my most recent attempt I have encountered a problem when exporting PDF of InDesign page that incorporates a page background 20% gray screen to iPhoto. A white half-inch white border runs around the perimeter of the image. This occurs even when I extend the bleed -- both in InDesign and Acrobat PDF -- far beyond the page border. All non-screen pages exported to iPhoto are fine. Is anyone out there familiar with what a workaround might be? In the enclosed screen shot, you can see the white order top and bottom, even though in InDesign the screen reaches all the way to edge.Thank you.

[Edited by Moderator]