there are some questions, in order to try to detect possible cause:
Is QV web server running on IIS or its web server?
Is WebParts license activated?
Which components configuration scenario is used (from the WebParts Installation Manual)?
One of the installation steps was to enter ajax virtual folder url. Have you verified that connection during installation?
Could you access to accesspoint portal from the SharePoint server using QV web server url that you entered as part of ajax virtual folder?
Have you configured QV Server to connect to that QV web server?