Using Registry to install Excel AddIn - excel

Question

I created an excel Add-In called
Project Count_Per Person.xlam
When I open up excel and go to Development>AddIns and select my AddIn to install, it does not stay installed if I close out of excel even after saving. The AddIn I made, creates a new MenuBarButton under the tab 'AddIns'
So I created a new registry Key to install the addin at startup under
HKEY_CURRENT_USER\Software\Microsoft\Office\Excel\Addins\ProjectCount_PerPerson
The Key looks like this
(Default) REG_SZ (value not set)
Description REG_SZ Project Count_Per Person
FriendlyName REG_SZ Project Count_Per Person
LoadBehavior DWORD 0x00000003 (3)
Manifest REG_SZ C:\Users\b012918\AppData\Roaming\Microsoft\AddIns\Project Count_Per Person.xlam
When I start Excel, it displays that it is installing the AddIn, but then I get an
Exception reading manifest from
file:///C:/Users/b012918/AppData/Roaming/Microsoft/AddIns/Project%Count_Per%Person.xlam:
the manifest may not be valid or file could not be opened.
http://pastebin.com/bN1datV5
Any insight into what I'm messing up would be beneficial.
Additional Information:
If the addin is uninstalled when I start excel, it gives the manifest error. If the addin is 'checked' when I start excel, it gives the download error in the comment below. Even if the addin is previously installed, the CommandBarButton does not stay in place. Also, under options--> addins the addin is stated to be "Active".

Answer 1

Just to clarify, there are two types of addins for Excel (and the other Office apps), VBA addins and COM addins. A COM addin is developed via Visual Studio and the Visual Studio Tools for Office. That is what brett s is referencing to.
But the more likely type are normal VBA Excel Addins, typically distributed via a .xlam file.
In order to load such an addin automatically for a user, you need the addin file on some local directory on the machine and reference it via the Registry.
For Excel 2010, a REG file to load the corresponding registry key is:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Excel\Options]
"OPEN"="C:\\Path\\To\Addin\\Addin.xlam"
This way the addin is loaded everytime you start Excel.

Answer 2

I Built an Add-In called 'FirstExcelAddIn' with Visual Studio, and checked to see what it did when It built the Registry Keys. I had my registry correct from the keys shown in the question, I just did not have all the files it was looking for in a COM addin.
Here is what my functioning addin looks like in the registry
(Default) REG_SZ (value not set)
Description REG_SZ FirstExcelAddIn
FriendlyName REG_SZ FirstExcelAddIn
LoadBehavior DWORD 0x00000003 (3)
Manifest REG_SZ C:\Users\b012918\AppData\Roaming\Microsoft\AddIns\FirstExcelAddIn.vsto|vstolocal
Here are the files that need to be present in the folder for the addin to work properly
FirstExcelAddIn.dll
FirstExcelAddIn.dll.manifest
FirstExcelAddIn.vsto
Microsoft.Office.Tools.Common.v4.0.Utilities.dll
I suspect that if you went through the effort to write your Add-In from scratch without tools, you would only need the '.dll' and '.dll.manifest' for your addin to work.