Outlook 2003 Show number of unread items

Dear all,

I have a exchange 2003 server and a mix of Outlook 2000/2003 clients.
I have in the Exchange’s public folder a folder containing task items.

I want to select show number of unread items for this folder but I can’t because it’s grey.

I have unsuccessfully try with differents users (Even administrator) and differents users r?les.