One of out customer installed multiple add-ins.
Our older version worked on his machine but not the newer version.
Disable or remove all other add-ins from Outlook add-in manager, re-enable
or reinstall our add-in won't work.
Reinstall Outlook won't work.
Add VSTO environmental variable does not help, not showing or logging
anything.
The loadstatus of registry key is the OK value 3 before uninstall and after
reinstall our add-in.
Other machines have no problem.

Any thoughts?