Scanners constantly rise problems. For instance, Panasonic multi printers may start to scan and then pop out an error:
Multi-Function Station Communication error has occurred. Check the device is power on and connected correctly.
It may sound odd, but the error message is actually correct in this case. Probably, the device is connected via a low-grade USB cable or USB extender cables are used. This may be confirmed by another error when connecting the cable to another USB port: USB Device Not Recognized. Replace the cable or disconnect all extender leaving only one cable, and scanning should work from now on.