The Suni system will return an image when no x-rays were fired at the sensor.
This problem has been traced down to the following problems:
The USB cable. Typically, USB cables of a length of 6' to 10' can result in this problem due to environmental noise being picked up by the cable.
Sensor Cable Problems. When sensors have been used for a while, the wires inside of the sensor cable can become twisted just like a phone cable does after a period of time (even though the cable shielding itself my not exhibit any signs). In some sensors, this can result in broken wire connections if too much stress is built up in the cable or in the separation of the cable connection from the sensor CCD (because a twisted cable is physically shorter).
The following resolutions can be used for each problem:
Replace the USB cable attached to the Suni system with either a shorter cable or a much higher quality USB cable of the same length.
You must get the sensor replaced by the distributor or hardware manufacturer.