have you asked CP to reset your downloads for Poser 6??

do so, and you will be able to download it. Also  bear in mind that Poser 6 is a big file (I think about 400MB so you will need a fast internet connection or a lot of patience!

And also there is a lot of traffic at CP these days because of the Poser 5 offer as well as the release of the g2 males package. 

Try not to stress out.

If you have the serial, you will be able to download the application. :)