Opening a pdf with runic symbols

Hi

I'm tryng to open a pdf file in illustrator that countains symbols (runes), and all I get is crossed squares.
Here's what I found so far :

-the ascii symbol displays fine in a browser or other app that uses system fonts.
-The document opens and reads properly in acrobat pdf reader.
-The document can be opened in google docs, the formating is messy but the symbols display fine.
-The formating in illustrator is fine, but all symbols are crossed squares.
-If I copy-paste, in illustrator, from the file opened in google docs, the regular alphabet displays correctly, but the runes show a crossed square.
-If I copy-paste the runic symbol from elsewhere, I still get a crossed square. I cannot change the font, it stays stuck on Myriad Pro.

Any idea how to solve the problem?