tagFormat : booklet command

[Emmanuel]

Hello,
After installing the full license of Minimserver, I immediately wanted to configure Minimserver to scan booklets named 'booklet.pdf' in the album folder.
In Properties > Advanced > tagFormat I added the following command:
Comment.displayFormat={$*infoFileURI^Digital booklet$comment}

However, when I rescan after saving the changes I get the following error message:
Incorrect tag name 'Comment' in property 'tagFormat'

Any idea how to fix this pls?