Latex often generates (by default?) text using a font which is of the type "Type 1 Symbolic". This is a very old type of font (now deprecated ) which is supported by Acrobat and Reader's PDF engines, but is not supported by the PDF engine used by Digital Editions. Since we do not know which font you are using, we cannot be sure, but suspect this is the case. Can you tell us exactly what font(s) you are using? Thanks.