SATA Ultra 16, 250GB, 7200RPM, Serial ATA/150 16MB Cache.

I just installed a Maxtor internal drive to my G5 S/P 1.8, The drive is a SATA Ultra 16, 250GB, 7200RPM, Serial ATA/150 16MB Cache which according to the Maxtor website it is compatible with my G5. http://www.maxstore.com/product.asp?sku=2565011 My question is that why under System Profiler>Hardware>Serial-ATA>S.M.A.R.T. status: it says not supported. Did I purchase the right drive? Am I doing something wrong? Please help. Thank You.