Issues outlook addin

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C#

Outlook

AddIn

I developed an outlook add-in on visual studio 2013 then build to the MSI installation by InstallShield and setup registry in my MSI config file follow 2 way below :
HKEY_CURRENT_USER :
+ HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins
+ HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\FormRegions
HKEY_LOCAL_MACHINE :
+ HKEY_LOCAL_MACHINE\Software\Microsoft\Office\Outlook\Addins
+ HKEY_LOCAL_MACHINE\Software\Microsoft\Office\Outlook\FormRegions

I created outlook add-in with the vsti file named 'abc.vsto'

For the first installing, it work fine.

After that i changed the name of vsto file from abc.vsto to def.vsto for creating new MSI installation.

But there are some issues happen after i installed add-in from the new one.

1. It's always show Formregion with empty control, after three or four time restart outlook, it work well.
maybe there are some encounter happen with two vsto file or something wrong with registry.

2. I realized that the outlook always creating new *.ost file which named *(2).ost after everytime restart that make duplicating ost file
How can i control generate *.ost process of outlook or why is this happen ?

3. I use this function for getting current outlook email user but it always return null value.
Globals.ThisAddIn.Application.Session.CurrentUser.AddressEntry.GetExchangeUser();

I don't know if this issue related to question 2 or not cause if I remove all *.ost file then restart outlook, in this case, the new *.ost file
was auto generated and add-in work well.

What I have tried:

I had take a lot of time for searching solution but have no idea founded.