Reusing drive enclosure for MyBook Premium with newer drive (1.5 TB Cavier Green) Possible?

My drive had a head crash so I removed the old 500GB WD5000AAJS drive and poped in a newer 1.5 Cavier Gree 1.5 TB drive. but while all connections fit fine andit powers up, it is not recognized by Mac OS 6.7.  

Is this just a jumper problem or is there more I need to know and do?

Will report back on the fix when found.

Well being that the enclosure is not encrpted it should be a problem. But remeber the drives come preformatted as NTSF for windows. For mac its going to require reformatting.