The customization cannot be installed because another version is currently installed...."
This issue may be caused if you have built the addin in debug on your machine and it is also installed from the deploy location.
- Open “COM Add-ins” form by either
Going to the Developer ribbon and click on the “COM Add-ins” button
Or going to the "File" ribbon and click on the "Options" button. Then under “Add-Ins” select “COM Add-ins” and click “Go…”
- Select “Excel Addin Script Help” and click the button “Remove”
- Then you’ll need to uninstall the Addin from "Programs and Features"