Migrating nodes with multiple terms and vocs

We want to move our drupal 5 site to our drupal 7 build. When I migrate 100 nodes with their taxonomy (4 vocabs) , 20 fail giving me this error:

PDOException: SQLSTATE[HY000]: General error: 1366 Incorrect integer value: '' for column 'tid' at row 1: INSERT INTO {taxonomy_index} (nid, tid, sticky, created) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3); Array ( [:db_insert_placeholder_0] => 8809 [:db_insert_placeholder_1] => [:db_insert_placeholder_2] => 0 [:db_insert_placeholder_3] => 1163099397 ) in taxonomy_field_insert() (line 1728 of /var/www/eci-d7/modules/taxonomy/taxonomy.module).

I use this query while migrating the nodes:

    $query = db_select($source_db_name .'.node', 'n')
      ->fields('n', array('nid', 'vid', 'type', 'title', 'uid', 'status', 'created', 'changed', 'comment', 'promote', 'moderate', 'sticky'))
      ->condition('n.type', 'article', '=');
      
    $query->join($source_db_name .'.node_revisions', 'nr', 'n.vid = nr.vid');
    $query->addField('nr', 'body');
    $query->addField('nr', 'teaser');
    
    $query->join($source_db_name .'.users', 'u', 'n.uid = u.uid');
    $query->addField('u', 'name');
    $query->orderBy('n.changed');
    
    $query->leftJoin($source_db_name .'.term_node', 'tn', 'n.nid=tn.nid');
    $query->leftJoin($source_db_name .'.term_data', 'td', 'tn.tid=td.tid');
    $query->addExpression('GROUP_CONCAT(DISTINCT tn.tid)', 'tag_list');

    $query->groupBy('n.nid');

I'm mapping the fields like this:

$this->addFieldMapping('field_tags', 'tag_list')
     ->separator(',')
     ->sourceMigration('EciLeTaggingTerms')
     ->arguments(array('source_type' => 'tid'));

    $this->addFieldMapping('field_tags_country', 'tag_list')
     ->separator(',')
     ->sourceMigration('EciLeCountryTerms')
     ->arguments(array('source_type' => 'tid'));
    
    $this->addFieldMapping('field_tags_blog', 'tag_list')
     ->separator(',')
     ->sourceMigration('EciLeBlogTerms')
     ->arguments(array('source_type' => 'tid'));
     
    $this->addFieldMapping('field_tags_encyclopaediae', 'tag_list')
     ->separator(',')
     ->sourceMigration('EciLeEncyclopaediaeTerms')
     ->arguments(array('source_type' => 'tid'));

And do the following in the prepareRow function:

     $tags = explode(',',$current_row->tag_list);
  	
     $query_source = db_select($source_db_name .'.term_data', 'td')
      ->fields('td', array('vid','tid'))
      ->condition('td.tid', $tags,'IN')
      ->condition('td.vid', '12', '=');
      
    $query_source->addExpression('GROUP_CONCAT(DISTINCT td.tid)', 'tag_list');
    $query_source = $query_source->execute(); 
    $newVoc = $query_source->fetchObject();
    $current_row->field_tags = $newVoc->tag_list;
 
    $query_source = db_select($source_db_name .'.term_data', 'td')
      ->fields('td', array('vid','tid'))
      ->condition('td.tid', $tags,'IN')
      ->condition('td.vid', '4', '=');
      
    $query_source->addExpression('GROUP_CONCAT(DISTINCT td.tid)', 'tag_list_country');
    $query_source = $query_source->execute(); 
    $newVoc = $query_source->fetchObject();
    $current_row->field_tags_country = $newVoc->tag_list_country;
    
    $query_source = db_select($source_db_name .'.term_data', 'td')
      ->fields('td', array('vid','tid'))
      ->condition('td.tid', $tags,'IN')
      ->condition('td.vid', '6', '=');
      
    $query_source->addExpression('GROUP_CONCAT(DISTINCT td.tid)', 'tag_list_blog');
    $query_source = $query_source->execute(); 
    $newVoc = $query_source->fetchObject();
    $current_row->field_tags_blog = $newVoc->tag_list_blog;
    
    $query_source = db_select($source_db_name .'.term_data', 'td')
      ->fields('td', array('vid','tid'))
      ->condition('td.tid', $tags,'IN')
      ->condition('td.vid', '10', '=');
      
    $query_source->addExpression('GROUP_CONCAT(DISTINCT td.tid)', 'tag_list_encyclopaediae');
    $query_source = $query_source->execute(); 
    $newVoc = $query_source->fetchObject();
    $current_row->field_tags_encyclopaediae = $newVoc->tag_list_encyclopaediae;

When i don't map the terms all the nodes get created.
I have no idea why with some terms I still get the error, and others not.

Can someone help me? I'm out of ideas.