I have a WD Mybook 3tb usb3 external drive that I use for backups and to store some media files. I've been thinking that I would get better read and write speeds if I took the drive out of its case and installed it directly in my mac pro. Well I did this, however, it says the hard drive can not be read. Upon putting the drive back in its case and connecting via usb, it is recognized just fine. What am I missing here? The drive is already formatted for Mac so I don't understand what the issue could be.