I did exacly this. And then zip the folder again? I used Winrar and compression method: best, but the file was still 600MB not 300MB like the original. I also tried compression method "none" but the file is not flashable. After the adjustment the only thing different is, that there is no explicit error message.
Should i try edditing the ro.build.product with an build.prop editor?
EDIT: Someone in a german Forum gave me this advice: Manually flash the boot.img an flash cm via this recovery and everything works. Hofe i could help a few with the same problem