I have exported an addressbook from an account to a .nab file. Now I want to import this .nab file into another account. Easy enough, but it doesn't work.

When I import the .nab file it doesn't do anything. I says that the import is completed successfully, but stays at "0 of 0" and the addressbook stays empty.
(This is the same when either the language is set to English or Dutch.)

What can I do to import this file? I think there is nothing wrong with the file itself and it was exported by the same version of Groupwise, being 8.0.1.