The scan function in PERFOMaster does not work.

Check if a TWAIN interface is installed. Maybe you may need to remove the TWAIN driver and then re-install a newer version of the driver. Check if your scanning device is connected, switched on and ready for operation. When you have more than one TWAIN device installed on your computer, it is necessary to select the TWAIN source for the device in PERFOMaster (Button "Select TWAIN-Device").