[O] Images not showing up in PDF output

[Mark S.]

Hello,

I was able to export a subtree as PDF, but the images don't show up. The images 
do export in HTML, and I can see that there is LaTeX code for it. It looks like 
this:

  \includegraphics[width=10em]{./Periodicals.org_20140402_202538_4928DjL.png}

Are there settings or additional add-ons that I need to produce the images?

Thank you,
Mark

Using MikTeX 2.9 under Windows XP with Org-mode 7.5