You can check the path of your Poser library folders by hovering over an item in the library - if hovering doesn't show the path, change the library options so that it does . As ghelmer said... make sure you install V4 into the runtime that shows up there.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)