Thanks for your post.
Are you able to view the converted PST & messages in Outlook client?
Unfortunately we do not have any experience with dtSearch and its Outlook plug-in. If you can view converted PST in Outlook client then the issue could be relate to dtSearch. In that case, you may need to contact dtSearch for more information.
In case it helps, following dtSearch knowledge base article contains information about troubleshooting Outlook index:
How to index Outlook and Exchange messages with dtSearch