Ah-HA! Is this the Metacreations P4 or the CL P4? When Meta dumped their graphics to work on web content, there were several groups of valid P4 restration numbers that didn't make the move with it. Both Vue and Poser are loaded with the invalid numbers, so that they won't work with them (the vast majority of them are the warez'ed copies of P4, but those valid numbers got lumped in there by accident). Contact CL directly about this, with your registration info, and if it checks out they will send you a replacement number that will work with not only Vue, but the latest updates to P4. If the S/N was ever warezed, then you'll have to prove you purchased the copy of Poser with a sales receipt.