I forgot to mention the hard drive(s) that I tried will not work internally but all work on usb external. Why?
How old is the MacBook? If its older you may be putting a SATA2 HD on a system that can only recognize SATA1...or some similar type of incompatablity. Most newer (2009+) can recognize SATA2. What is the year/model of the Macbook and what is the make/model of the hard drive?