There's lots of possible reasons: -
- You might need an external case using two USB ports (one USB port may not provide enough power). OR
- a firewire powered case (same reason), OR
- the SATA adaptor is for SAT II not SATA I (as your 6 year old drive is likely to be). OR
- the drive is dead
It's pretty hard to diagnose these things long distance. Only you know if you've verified the connector you chose supports the speed of the old drive.
A last resort workaround would be to find a working machine similar to your old one and see if swapping the drives will allow a boot... if it does that means the drive is not your issue. Reboot connected to the network and follow the directions under Migration Assistant OR target boot the drive directly connected to your new machine.
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