Before you removed the defunct drive, did you choose the option in ServeRAID to replace the drive?
Early versions of ServeRAID made you do this. You might have to stick the old drive back in, tell ServeRAID you're going to replace the drive, then do the replacement.
I know with 6.1 and above you don't have to do this, you just remove the drive and put in the new one and ServeRAID will rebild the array automatically. With an older version, I had to put the old drive back in, tell it I was going to replace it, then actually do the replacment before it worked.
This was using a 3H controller.
I'm Certifiable, not certified.
It just means my answers are from experience, not a book.