In reply to Paul:
Well, version 12 is the best available version, optimised to cope with pauses, hesitations, etc. (according to Nuance, and it is is probably true), so I don't understand the problem...I wrote to my contact at Nuance to see if they have already heard of such a problem. They are going to download Studio 2014 evaluation version to make their own tests.
Personally, I tried again with long pauses and it works correctly...
This being said, when using Dragon in a CAT tool, it is alwaysbetter to think about the translation before dictating it and to dictate a sufficient portion of text, also to give Dragon enough context to produce a good result