Comment 19 for bug 864271

I correct my problem as follows:
1) run initramfs with -o (output option)
sudo initramfs -o initrd.img-3.0.0-12-generic-pae 3.0.0-12-generic-pae
Now the initrd is generated. (I don't know how I miss the -o option)
2) Them reisntall the linux-image-3.0.0-12-generic-pae package from synaptic
(otherwise the I had kernel panic).