Outlook 2010 don't associate .DWG to open file in mail

DraftSight v1R1.4 is installed and activated in a new laptop (Windows 7 Pro 64bits)

DWG files are open correctly in the explorer, with or without DraftSight previousely opened.

The Problem is in Outlook 2010 : It's impossible to open the file in a mail, nothing is happened : the application don't start and no error message is displayed. The file is correctly opened if DraftSight is previousely opened.

It's as the old outlook express & powerpoint viewer problem with a command "View" had been have to change in "open" in the registry...

Best Regards