DataObject: getLink

Hello I have 3 tables that build together a m:n relation. Table tb_A has a filed (integer) called id_A Table tb_B has a filed (integer) called id_B Table tb_C has a filed (integer) called id_C and the keys from table A (id_A) and table B (id_B) My (test-) code looks as follows: $tb_A = new DataObject_A(); $tb_A->id_A = 5; $content->find(); while ($content->fetch()) { $c = $tb_A->getLink('id_A', 'tb_c', 'id_A'); $str = "id_A: " . $tb_a->id_A . " references in tb_C id_B: " . $c->id_B . "<br>"; echo $str; } This code does not work as expected. The return from $tb_A->getLink is false. According to the manual, the while-statement should be: while ($content->find()) { ... but this results in an endless loop. Can anybody tell me what I am doing wrong, please. I would also be glad the get tips how to process such a m:n relation effectively by using DataObject. Thanks a lot! -- Cheers! Marco