Please also make sure, that you the option No double data records is enabled.
This solution assumes that the Album ID is stored in the comment field. If you are interested in a english overview of all placeholders available for the export, please have a look at this topic at the Hydogenaudio Forums.
It seems, that Mp3tag has some problems with trailing spaces at the lines of export configuations, so I've sent you an email with the mte-file attached.
Simply copy the content of the file to the configuration at Options, Export.