How to mount a luks encrypted partition at boot

I have been given a task to creat a LUKS encrypted partition and then mount it, here are the steps I followed:

1. Create the partition for encryption:

   sudo fdisk /dev/sda
   

2. Reboot

3. Format the partition with cryptsetup:

   sudo cryptsetup luksFormat /dev/sda3
   

4. Open encrypted partition:

   sudo cryptsetup luksOpen /dev/sda3 secret-disk
   

5. Add the following to /etc/crypttab:

   secret-disk       /dev/sda3
   

6. Make filesystem on partition:

   sudo mkfs -t ext3 /dev/mapper/secret-disk
   

7. Make mount directory:

   sudo mkdir /secret
   

8. Add the following to /etc/fstab:

   /dev/mapper/secret-disk   /secret   ext4 defaults 1 2
   

9. Mount partition at /secret:

   sudo mount /secret OR sudo mount -a
   

10. Reboot.

Problem: During reboot, the mount instruction in fstab returns the error : device not ready or not present. And I have to enter S to skip the mount so ubuntu can boot or M to recover it manually. I have checked this option but it does not solve mine. How do I get the encrypted partition to mount at /secret.