This is normally caused by having Word accessibility tags in the document template - when exporting to PDF, PowerPro will raise this error:
 
 
 
 
 
 
 
 
You can test this by opening your template in Word and trying an export it directly to PDF -  you should get this error:
 
 
 
 
 
 
To fix this issue, either remove all Word accessibility tags from the template document or create a new template document without Word accessibility tags