Carrara can read directly from all runtimes. So, if the runtime is working in Poser/DAZ, then it will also work in Carrara. However, the import/export thing is obviously not playing nice. (btw, this isn't all that uncommon in other CG software either - the plugins alwas seem to have 'opportunities' to fail)

To ask a silly question, have you tried simply building the scene in Carrara and bypassing the use of multiple programs. Carrara's claim-to-fame is that you can do everything in it, precluding the need for plugins. 

Mark