Unable to see disk in "Startup Disk" in preferences

Hi all

I have a Mac Pro 1,1 which I have upgraded and installed 2,1 firmware.

I'm using a Crucial M4 SSD connected on SATA.

I installed El Capitan using Piker Alpha's boot.efi, following this youtube video

My system works perfectly however I can't select my SSD in "Startup Disks", so it's causing me problems when I want to bootcamp the machine or switch between Lion and El Capitan, please see the attached screenshot. The machine boots up but only if my SSD is the only drive, otherwise it boots into my other HDD which contains Lion, and i'm unable to boot back into El Capitan as my SSD does also not appear in the startup disks from the Lion install.

Does anyone know how I might be able to fix this problem?

Thanks in advance