Kurka, there is no such thing as a Poser 5 or Poser 4 export format, they both exports to the same format: pz3. The problem here lies in the fact that Vue needs a valid installation of Poser 4 in order for the pz3 import to work. Until Vue recognizes a valid Poser 5 installation, you will need Poser 4 installed, regardless of which Poser version that created the pz3-file in question.