OK, drive configurations are tricky. The first drive has to be on the first POWER lead of the leg. If you are attempting to provide power to a drive from a second or third power slot on the cable, and are expecting the drive to load the OS, it will not work. Always label where things came from, so you can take your working model and apply that model to your newest configurations (reverse engineer the connections!)
Let us know if you have checked what power "leg" you are using. It must be the first one!