Raid 1 keeps Rebuilding Question

[Malam]

I am trying to setup a Raid 1 using the Nexstar MX enclosure. The enclosure's eSata is attached
to my motherboard's Jmicron port. Yesterday it started rebuilding. This morning I found the two Hard Drive access lights on the enclosure blinking, so I assumed the rebuild has finished. I rebooted my system, but the enclosure is showing that rebuilding is stated again ! Now its at 35%. How ofter does a Raid 1 system need to rebuild ? Is rebuilding a continuous process with raid ? I have not loaded any file to the main drive.
I am getting frustrated.