Image links break in html output from one ditamap, but work from another ditamap with the same xml

Hi!

I publish Responsive html5 from ditamaps (without robohelp, just FM's own publishing tool). Now, these ditamaps include partly the exact same xml files. However, when a same xml file with the same images come out fine from one ditamap, the images don't appear when publishing the exact same xml file with another ditamap. The place for the image is just empty with a broken image/file path icon. I assume there is something wrong with the ditamaps, since the xml files publish fine when published as individual files. Anybody have any clues what might be the issue?

Thanks.