Image size doesn't match the expected size

Hello, I have a problem when trying to Install Full ROM Firmware on my Chromebook, it puts me an error saying :

Error : Image size (8388608 B) doesn’t match the expected size (16777216 B) !

Are you using the MrChromebox script? Internal flash? External flash?

Yes I am using the MrChromebox script

I can send you the photos of the error log :