Problems with Dual drive carrier.

I replaced my optical drive with the iMac & Mac mini Dual Drive Enclosure

It worked! My iMac found the new disk and all is fine and dandy (I think)… But it disappeared from the Finder a while here, which I don’t understand why? But now it’s back, so I’m hoping for the best! :)

And now it is gone again.. anyone got a clue as to why this happens? I want to install OSX on it, but that is impossible when it isn’t usable all the time.

This hard drive is not visible while starting up the system, or when trying to install OS-X on it. But I can see it when OS-X is started.

Am I missing something?