Macbook Pro 13" - SSD not detected via SATA

Hi everyone,

I've recently purchased a SSD for my macbook just to give it a little extra punch. The drive however doesn't appear to be detectible when attached via the internal SATA input.

I have formatted the SSD to Mac OS Extended (Journaled) in a GUID partition. Then using an external dock, cloned my original boot and recovery partitions to the new drive using Carbon Copy Cloner. I can now boot via the usb connection to the SSD drive but if I install it inside the macbook it can't be detected. I followed this tutorial https://discussions.apple.com/docs/DOC-4741.

I can boot from my original drive via external usb and internal sata. I can also boot from my ssd drive with the external usb connection but not from the internal sata connection. I am using the original hard drive connecter, not anything to do with the superdrive.


Details:

Model Identifier - MacBookPro 9,2 (13" Mid-2012)
SSD Drive - Plextor PX-256M5S 256GB 2.5" 6Gb/s
Operating System - OS X version 10.8.5 (Mountain Lion)


I hear that some people with similar issues replaced the sata cable and this resolved the problem, could this be a viable solution or just shooting in the dark? Any help is really appreciated guys.

Cheers,
Josh

Update:

A mate lent me his sandisk ssd with mavericks installed. It had exactly the same issues as the previous one which means it's most likely the macbook itself.

Any suggestions?