How to add a second data file to Outlook 2007?

I have 2 accounts on my laptop running Vista Home Premium and Office 2007. One for me and one for my wife. Currently she can't see any email received using my account. The goal is to see all email messages both for her and me.
Data files were stored in different locations
C:\Users\<me>\...\Outlook.pst and C:\Users\<wife>\...\Outlook.pst. Well we couldn't see inbox of each other while we are sharing the same email address.
I wanted to add her data file to my Personal Folders and my data file to her
respectively.
When I try to add the data file I've got the error:
"The file C:\Users\<wife>\...\Outlook .pst cannot be opened". I check that I
do have Full permissions for this file.
What I'm doing wrong?
Thanks in advance.
susja

When you say accounts do you mean two separate accounts in vista or two profiles in outlook – or both?
There should be no problem adding a second user PST file into your account using data management in outlook or mail in control panel and if using a single email address and wanting to download the messages into both profiles you need to make sure that a copy of the message is left on the server.

Sorry that I haven't been clear.
I mean that I have 2 accounts on my Vista: one for me and one for my wife. Profile for Outlook is one. The only difference is that I start it either as myself or she starts with her account. The problem is that when I receive a message and then she starts Outlook she doesn't see it in her inbox.
susja

Ok we can resolve this. First are both profiles using the same PST file and do both have this set as the default?

hello Wild,
again thanks for your respond.
It looks that I wasn't completely clear. I think that I have 2 accounts in Vista, 1 email account specified in Outlook and 2 profiles in Outlook respectively. Settings for Outlook are the same i.e. it's default except they use 2 different PST files. And the problem is that I can't add second PST file (either her or mine) .. it fails to open the second PST.
As you recommended I changed the setting for server and now mail isn't deleted from server for 10 days. Now I can see the same message using my wife and mine account and 2 different profiles respectively. That's good but it wasn't my goal. Actually I don't think it's good idea to save messages on server and also it won't work if one of us open his/her mail client after 10 days. The goal was to see the same messages using either of profiles.
Thanks again for your kindly response.
susja

Ok Susja let's concentrate on opening the PST file in the other user accounts
You said that you checked the files and you have full permissions but I think something was missed under the file properties/security tab
I will try to duplicate this myself unless someone else has done this sucessfully already

well
here is the security properties of PST file that I provide as an additional file.
I've got error "cannot open file"

Ok you can use the advanced and edit option and the tutorial is available there too. I would suggest you make a copy of the file first as a backup before changing any settings.

Well
as you could see both PST files already have Full permission for both accounts ... It's nothing I could do more.
It looks that I'll have to leave with a saving copy of email on a server for 10 days ( don't know the reasonable number of days ).
That way at least both of us will be able to see the same message.
Although I think it should be the way to do it the other way ( unless it's designed that way ).
Thanks a lot for you help
susja

I think we will figure out advanced settings some time. If you do not want to hold you email messages for 10 days then I suggest you open another email account and forward the messages from the first to the second, that way you could clear the server when desired.