Oh.. I found the problem.
Outlook disabled my add-in. I enabled it now
But I think there is still a problem!!
If your add-in disabled, and you uninstall it and re-install, then your
add-in will still disabled!!! Unless you run Outlook after the uninstallation
and before the re-installation!!!
I think this what happened on that machine. Outlook disabled an old version
of my add-in, and now this cause my new add-in with the same name to
initially disabled after installation!!!

"MON205" wrote:

Hello all,
My Outlook add-in works fine, I test it on several machines and all things
fine. But a problem found on one machine, that the add-in not loaded.
If you opened the COM Add-Ins dialog (Tools-Options-Other-Advanced
Options-COM Add-Ins), in this dialog I can find my add in not checked. If I
checked it and pressed OK and then come back to this dialog it'll be
unchecked again, and the add-in still unloaded.
I checked my dll dependencies but nothing missed.
I registered my add-in another time just to be sure and it registered
successfully.
Any help in this?

Thanks