[Fedora-livecd-list] live initrd for a custom kernel

Hello everybody, I managed to build an RPM of my customized kernel, livecd-creator installs it just fine, and generates its initrd file which is apparently weird (9MB !), this initrd couldn't boot my kernel, and it says that it couldn't find the root filesystem. I know that Fedora kernels don't have this problem, but why? What should I do to make a basic initrd for my custom kernel to make it boot properly? Thanks in advance. Regards