1, the meter itself failure: may be the meter internal failure caused by the needle does not go. You can consider replacing the meter or repairing the meter.
2, poor cable contact: check whether the cable connection between the two ends of the meter is firm, whether it is loose, off or damaged and so on.
3, transformer failure: transformer failure may lead to the emergence of unstable voltage or provide insufficient voltage value, resulting in the meter does not work properly.
4, line failure: it may be that the line failure leads to the current can not flow normally, may also affect the normal operation of the meter.