I'm having a problem with accepting share requests via the Groupwise SOAP API for some users.

We use the sharing feature to pull contact lists out to our communication clients. My application log in via the SOAP API once in a while to check for new share request and accepts them if they are valid. For most of our customers this is working very well, but we have run into a problem with one customer.

The problem is that Groupwise returns an error the first time we try to accept a share request from a user, the user then has to send another share request which then works. This is consistent across all users for this specific customer.
I have double checked this several times and every time we get the error "Personal address book: No book record" for the first request and an OK for the second (the funny thing is that the two share request is for the same resource...)

Any ideas as to what could be the problem?

The customer is running GW8.
The only difference between this and our other installations is that the groupwise user we use for the SOAP API is located on a different postoffice than the normal users. Could this be a problem?