Dual Drive not working, how to test the single parts?

Recently I bought the dual drive enclosure for my MacBook Pro 13 Unibody Mid 2010. I tried to install it going thorough the step by step guide (Installing MacBook Pro 13" Unibody Mid 2010 Dual Hard Drive) using the tools that I bought with the kit. The installation went smooth, but when I turned on the laptop the second drive was not recognized by the system. So I decided to remove the hard drive and restore the Super Drive, but also this one now is no more working. Then I made the following checks:

1) I connected the hard drive directly to a PC and it is working correctly. (it is the original macbook hd)

2) I tried to connect to three different computers (with unix, win and os x) the hard drive through the enclosure and the SATA connector provided in the kit. But in this way the drive is not working.

Are the enclosure, the internal connector or the SATA interface of the macbook broken? How can I check them?

Thank you,

Andrea