The vsto is only automatically updated from the server from which it was originally installed.
If it has not updated when the server is updated with a newer version of MerlinXL it could be because of one of two reasons:
1. The vsto was not installed from the server that has been upgraded.
2. The vsto is not set to update everytime Excel is opened.
To manually update the vsto:
1. Open Control Panel
2. Open Uninstall a Program
3. Locate the MerlinXL application
4. In the bottom of the panel see the “Update Information”
If it is the server listed in the Update Information is the one that has been updated, click on the link to update the vsto from the server
If the Update Information is pointing to a different server, Uninstall the Vsto using the Uninstall button
Open Internet Explorer and enter the Merlin url to the updated server
Install the vsto from the updated server