I found a good deal on a Toshiba 3.5'' 1.5TB external HD, and bought it just to remove the disk and place inside the computer. Then I tried to use the enclosure as a SATA to USB converter, and it didn't work with two different 2.5'' HD. It is no recognized by the computer.
I placed the original 3.5'' HD and it worked. So it is really some kind of incompability.
Actually one of the 2.5'' was from Toshiba also.
Why can this happen? isn't the 2.5'' HD just like the 3.5 on power and interface?
Your enclosure may have some circuitry specifically designed to look for certain HDDs. If it fails to find those models, it may assume that there is an error. Seems unlikely though.
When you installed the external device initially, did you install any software with it (from Toshiba)? Also, have you looked at your disk manager (control panel/administrative tools/computer management) to see if the new HDDs are seen but not partitioned/available?