Often times when SilverFast is not able to detect a Plustek OpticFilm scanner it will put out a "driver missing" notification error message.
This article will help you to reinstall both, TWAIN device driver and SilverFast, when you are working on a Microsoft Windows computer.
Please reboot your computer first. Make sure the scanner is connected and powered on.
The keyboard shortcut WIN+X will call a text menu on Windows 10 and 11 providing you with a range of helpful links.
The device manager is amongst those in the upper section.
In the Windows device manager, you will probably find an entry for your Plustek named "Filmscanner".
Right-clicking it you want to "uninstall the device". It's important that you check the box now to delete the driver from the system, before continuing.
After having deinstalled the scanner, you can turn it off.
Next please go to WIN+X -> "Apps & Features", and remove the Plustek OpticFilm software as well as SilverFast from the installation.
Now we shall be installing current versions of driver and software anew.
For SilverFast 9, please log in to your my.silverfast.com account. Here under -> "Manage Licenses", you can download the current SilverFast 9 installer software.
Plustek did put online their drivers on the web page https://plustek.com/eu/support/drivers-and-downloads.php. The file you are downloading is a ZIP archive, and it is suggested to expand this before running the installation.
After the download is completed, you will find it usually in your user's "Downloads" folder. Right-clicking the file gives you a number of options, including -> "Extract all..."-
After that, you can run the installer from the extracted folder.
As soon as the desktop comes up, you may power on the scanner again.
If you find that above steps cannot resolve the situation experienced yet, please check if the scanner can be detected fine, if you would use a different USB port on your computer.
Do also try to use a different USB cable, preferably one you know of works alright with another peripheral device (e.g. a USB printer).
Should SilverFast further fail to detect the scanner, but it is also not should in the device manager, neither under the "Imaging devices" section, nor as an "Unknown device" or "Other device", you might have a hardware-related issue.
Then you could check how situation is if you would try the scanner at another computer.
You will probably also want to seek assistance from Plustek support staff:
https://plustek.com/us/about-us/contact-us.php
On the other hand, should scanner detection operating system wise seem to work smoothly, but only SilverFast refuses to connect, two further measures are suggested.
Please find the chevron near the clock on the right of the Windows task-bar. Clicking it to reveal a number of background software, move the mouse cursor above the entries, and find "Quickscan".
Right-click and quit it.
Also Microsoft's own WIA service can be a problem. Using the keyboard shortcut WIN+S, entering "service" (without the "") you can -> "run as administrator" this system utility.
Scroll down the long list and look with the "Windows image acquisition (WIA)" service, and right-click to stop the service, then double-click the entry to modify its start mode. Switch from automatic to -> "Manual".
Good success!