x86_64: grub-install for secure boot

[Zvi Vered]

Hello,

I'm trying to install grub 2.x for secure boot .
I did the following steps under knoppix 9.1 :

mkfs.fat -F32 /dev/sdb1
mount -t vfat /dev/sdb1 /media/sdb1
apt-get install grub-efi-amd64-signed
grub-install --boot-directory=/media/sdb1/boot --efi-directory=/media/sdb1
--uefi-secure-boot

But when I selected this device in the boot menu I got the red message
telling this partition contains unsecured code.

Can you please advise how I should proceed?

Thank you,
Zvika