What model Macbook do you have and what SSD did you get? Did you install OSX onto one of the drives already? If you put the SSD in place of the old hard drive... that shouldn't give you any problems. Pull out the caddy and see if you can boot from the SSD in the stock location. One a separate note... I put a OCZ SSD into a caddy replacing the optical drive for a friend this weekend (Macbook Pro Late-2008 15"). A got the Fusion drive software working... pretty neat. Seemed pretty fast but didn't have it long enough to test. Told friend to keep me posted.