PSU readings............

[Flybywyre]

Can any one tell me if the following readings are correct. The + readings seem to be OK but I do not understand the - readings

+ 3.3V Voltage 3.28 V
+ 5V Voltage 4.89 V
+ 12V Voltage 11.80 V

- 12V Voltage 1.05 V
- 5V Voltage 1.99 V

Thanks