Delegate access

[nancyl]

I have delegate access to someone's mailbox, but when I
try to put it on my folder list, I am able to do so, but
when I actually click on the name/mailbox to open it
further, I receive the following message: "Unable to
expand the folder. The set of folders could
not be opened." A right click results in the same error
message. When I click ON the Mailbox folder, I get a grey
screen and it says:"Unable to diplay the folder. The
operation failed."
What's strange about this is that I AM able to see her
mail/calendar, etc, when I use the open other user's mail,
etc. I am able to fully go in, add, delete, etc. Just
can't put in it the folder list.
Any answers?