incorrect integer value when importing topics and posts

Hi,

I get the following error when I try to import categories:

Forum vid: 1
Error message
PDOException: SQLSTATE[HY000]: General error: 1366 Incorrect integer value: '' for column 'parent' at row 1: INSERT INTO {taxonomy_term_hierarchy} (tid, parent) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1); Array ( [:db_insert_placeholder_0] => 15 [:db_insert_placeholder_1] => ) in taxonomy_term_save() (line 645 of C:\xampp\htdocs\japnorthwest\modules\taxonomy\taxonomy.module).

I've checked the code and data and I cant see the problem at all. All of the values look like they are integers in the temp table that the module creates.

Any help please?

Thanks,

Paul.