How can i save a Publisher document that has an image with an semi-transparent overlay to pdf?

I developed a mat in Publisher by inserting a picture and then overlaying that with a text box whose background was semi-transparent.  It saves as a jpeg, and can be printed from there, or printed directly from Publisher, of course, but when I try to save it as a pdf, I only see the overlaying text box with the background fully opaque.  Is there some trick to getting the pdf to just save what's seen, or am I missing a key control that needs to be set when saving?  Thanks.