Error 122 in my own cooked ExtROM file

[amir77a]

I am trying to cook my own ExtROM file.

I opened (using ER2003edit) the current 1.72.800, remove some files, add other files, and saved everything.

When I am trying to flash that file I am getting (running HimaUpgradeUt.exe) error 122 - Extended image file checksum error.

How can I fix this error?