What's the secret to Ext4 on >16TB?

[Michael Peek]

Ugh.

Disgruntled with JFS and XFS, I went through a lot of trouble to get a 
2.6.28 kernel compiled and running, along with e2fsprogs 1.41.4, all so 
I could format a large RAID (>16TB) with ext4 -- which, as I understand 
it, can support filesystems on the order of EB's...

So I can't figure out why I'm seeing the following error:

# uname -a
Linux bkup1 2.6.28-11-server #40 SMP Tue Apr 7 19:12:44 EDT 2009 x86_64 
GNU/Linux

# mkfs.ext4 /dev/raid-vg/raid
mke2fs 1.41.4 (27-Jan-2009)
mkfs.ext4: Size of device /dev/raid-vg/raid too big to be expressed in 
32 bits
    using a blocksize of 4096.

I thought ext4 was supposed to use 48 bits, not 32.  So what am I doing 
wrong?

Michael