Reason: Your e-signature device is not plugged into the computer or the computer does not recognise the device.
Solution: Check whether the computer recognises your device by plugging it into different USB ports. If there is a button on your e-signature device that moves the sim card, this button can move the sim card from the outside even if the cover of the device is not open and this causes the computer not to see the card.
When you plug the device into the USB port, both the blue and red lights should be on. If only the red light is on, this indicates that the computer does not recognise the device.