Sharing IMAP folders

Hello - I'm a new Community user who's been plunged into the world of Server Admin.

I am having a problem with sharing out IMAP folders. Currently we are running OS X Server 10.4.11. We have an number of projects in our office with IMAP mail folders associated to them. I wish to share some of these out with other users in the office (one user in particular which I will call "Client A" for our purposes)

After seeking advice through these Forums before, I successfully installed SirAdmin and assigned an ACL to the folders I wanted shared. Upon restarting the IMAP server and Mac Mail on the client machine "Client A" I was able to subscribe to the folder sucessfully and it did appear under "Other Users" as a shared IMAP folder.

HOWEVER IT DOESN'T DOWNLOAD THE MAIL THAT IS IN THE FOLDER. It is just showing me (in the left hand pane) the folder that I've subscribed to - but it is not receiving any mail associated with this

I have no idea what other options I have here (as I stated, I am a novice at Cryus...and using SirAdmin has simplified things greatly). The options I have selected in assigning the ACL to the mailbox are:

Look up name of mailbox

Read the contents of mailbox

Preserve "seen"/"recent" status

Write message flags

The client machine is running OS X 10.7.5.

It is worth noting that I have tried this (with a different IMAP mail folder) and it worked on the "Client A" machine. I was delighted it worked first time around - but now it seems that none of the folders I wish to subscribe to are appearing.

Any help you may have with this would be great!