ROM Hack Extracting from roms, Corrupted romfs?

[MisterMunchie]

Heyo folks!

I'm using Asia81's method on this page here. Once I get to the point where I have a decrypted romfs.bin file, I run into a problem. I'm trying to extract the data from the bin file using ctrtool but I get the errors

Error, IVFC segment corrupted
Error, RomFS corrupted

I've searched as much as I can to no avail. Any ideas?

Thanks.