Problem converting powerpoints to PDF

I have a powerpoint file and I can convert it to a PDF with the Acrobat plug in that is in PowerPoint. But, when I add a jpeg to a slide (and the slide consists of only a jpeg and a title on the slide, nothing else) and convert it to PDF the only thing that appears is the title. No jpeg. The jpeg size is 10x5.6 inches.

Anyone know why this is happening?

thanks