[eluser]OverZealous[/eluser]
1) Is it saving any relationships?
2) Does $b->save($d) work?
3) Are you able to save brainstorms manually, without the HTML form / submit?
4) Are you certain that $model and the $has_many item are spelled the exact same, on both models? I know you said you looked, but make sure there aren't any typos. Also, this assumes you are using standard, simple relationships, not the advanced relationships.
5) Have you tried outputting the queries using $d->db->last_query(), or even better, enabling the CI profiler, and looking through all of the queries?
6) Also, just because error is empty, doesn't mean that something didn't go wrong. When saving relationships, for example, you may get a FALSE response, but no error message. This means that the attempt to save the relationship failed, usually either $d or $b (in your example) are not defined (ie: do not have an ID set), or that the relationship is improperly defined.
This is what I mean by not enough information. Saying that $a->save($b) doesn't work just tells me that the problem is on your end. Obviously that code snippet isn't the issue, or no-one could use DMZ. (BTW: here's a smiley, I'm not angry :-P)
