Public Folder Reports under "Content Analysis | Public Folder Content" do not return any data. These reports include:
Population of these reports requires that an "Exchange Public Folder Content and Attachments" be run against any public folder stores that need to be reported on.
Run an "Exchange Public Folder Content and Attachments" Gathering against the public folder stores to be reported on by following this article:
https://support.quest.com/messagestats/kb/70888
For Additional information regarding gatherings required to populate specific reports see the "MessageStats - Reports User Guide"
Additional information regarding the "Exchange Public Folder Content and Attachments" gathering please see the section labled "Gathering Public Folder Content and Attachments" in the "MessageStats - Administrators Guide"
The Above referenced documents are included on the MessageStats installation Media within the Documentation folder, or they can be downloaded from the product documentation section of the supportlink website.