Cannot Boot Mac on New Clone HD

Hello,

I have been trying to upgrade the HD in my 2009 MacBook (not a pro but in a silver unibody) - model A1278. The stock 160gb HD has long been out of space and it was time to upgrade.

I selected this SATA II model which I believed would be compatable with my computer (http://www.amazon.com/Travelstar-500GB-Cache-Internal-0S02858/dp/B003SX0ORA/ref= sr_1_5?ie=UTF8&qid=1388789555&sr=8-5&keywords=2.5%22+sata+hard+drive) and cloned my HD using Super Duper via a USB connection.

I started by erasing the new HD in Mac OS Extended (Journaled) if that matters and partitioned in 1 section in GUID. After that I let Super Duper run it's magic with a complete file transfer. After which I was able to dismount and remount my new HD and it appeared in the Startup Disk Preferences and I was able to reboot to the New HD without any problems. I repeated this several times and everything was working wonderfully while connected to the new HD via USB.

However, when I tried to remove the old HD and replace it with the new my computer boots to the dreaded blue screen with a flashing "? file". When I boot holding options, it boots to an empty blue screen with a cursor.

I've taken the new HD back out, reconfirmed that it works via usb and reinserted many times. For the life of me I can not figure out what I am missing.

I've seen similar problems here: https://discussions.apple.com/thread/3358220?answerId=16273265022#16273265022

-but I am running OS 10.6.8, so that's ruled out

And here: https://discussions.apple.com/thread/5213947

-but I have a SATA II HD replacing my old drive.

Any thoughts, suggestions or words of advice are BEYOND appreciated!

Thanks!