problem with ecu flashing

[snikkels]

I wanted to go flashing my ecu with ecuflash but i can't.
If i do test flashing to ecu it's says

ECUflash 1.34

reading ecu programming voltage
[15:25:10.000] programming voltage is 4.34 volts
[15:25:10.000] programming voltage is out of range!

with this ecuflash i could always flashing my car.
Can someone tell me what this means?

And what to do about it.

Thanks,