Trouble with viewing .pdf links in Ss4 Composer or Ss4 Navigator

I am having trouble viewing some of the links... specifically, the .pdf files.

When the links (both .pdf files and the videos) reside within ProjectWise AND both the Composer and Navigator files, too, reside in ProjectWise, I can view the videos link (in Navigator, hover over element>rt clk hold > Open Link >select intended link>training video). When I do the same process to view the .pdfs it does not open.

Back checking - At the source .pdf file, when I double clk the file, it opens with no trouble.

Does anyone have an idea why one works (Training.wmv) and the other does not (.pdf)?