I don't have Poser reloaded yet from a computer change so forgive me if I get names wrong. I'll try this from memory since no one else has replied yet.
I think when you export an animated series the export window defaults to the first frame. If you change the number to the end frame then export your cloth morphs should stick.

Supposedly Bryce 7 will handle animations from poser when it is released. Till' then it's all done the long way by hand. Sorry!