LaserSoft Imaging

When trying to choose a plug in in the installation process, (silverfast 5) it doesn't allow me to choose anything. i click select and it seems to install, says it was successful, but it's nowhere to be found, before or after restart. what's the problem?

There need to be the Twain.8ba in the Import-Export Folder of Photoshop, else SilverFast Installer can't install correctly. This is at normal in there after a new installation of Photoshop.

kind regards