Outlook Addin Load behaviour

Check load behaviour
HKCU\Software\Microsoft\Office\Outlook\Addins\OurOutlookAddin.OutlookAddin
LoadBehavior: 3


0;Unloaded :Nicht automatisch laden
1;Loaded :Nicht automatisch laden
16;Loaded :Beim ersten Mal laden, dann bei Bedarf laden
2;Unloaded :Bei Start laden
3;Loaded :Bei Start laden
8;Unloaded :Bei Bedarf laden
9;Loaded :Bei Bedarf laden

Check disabled AddIns
HKCU\Software\Microsoft\Office\11.0\Outlook\Resiliency\DisabledItems


Uninstall Problems:

Typically, it is resolved by unistall the Add In from Add/Remove Programs list. And your OutlookAddIn should be in the list unless you delete the following registry manually.(HKCU\Software\Microsoft\Windows\CurrentVersion\Unistall\...)

Consequently, first, you need to make sure that your OutlookAddIn is really not in the list. If the answer is no, you can try to delete the following keys in registry to see if it helps.

There should be two sub keys related to your Outlook under:

HKCU\Software\Classes\Software\Microsoft\Windows\CurrentVersion\Deployment\SideBySide\2.0\PackageMetadata\{***}\

({***} is hash string different from projects)

Find and delete them.