CM11 is very special. You need to flash the kernel, the bootm.img that is inside the ROM's .zip. Flash it and then flash the ROM.
Again, if you are gonna flash another ROM first flash the correct kernel, let's say DooMLoRD's kernel for stock based like eXistenZ or the boot.img from CM10.2 ...after that you can flash the proper ROM
Just CM11 needs this.