Fonts not getting embedded in pdf

There is a Flag set with every font set by the designer of the font, whether or not the font could be embedded. AFAIK, lately it is made mandatory to follow the flags of such restrictions. Hence Since X5, users may get an error that a particular font cannot be embedded. This means that the font that you have used is set as not to be embedded.

And this is done by the font designer/manufacturer. CorelDRAW and any other software just follows the settings/restrictions.

Solution :
a) Use only the fonts that come with CDGS as these fonts may not have     any such restrictions.
b) Convert the Text to curves while making the PDF. (You may get a     heavier PDF file as a result of this)