Quicksilver B53 DMG Won't Mount

I just downloaded the QS.3815.dmg directly from the Blacktree website
and after expanding the compressed file using Stuffit and then trying
to mount the DMG I get a this system message:

Warning

Image                      Reason
QS.3815.dmg           no mountable file systems


The weird thing is that other DMG's mount fine. Just to be sure I
Repaired Disk Permissions and Rebooted, and still the DMG won't mount.
I am wondering if I am alone with this problem.

Any help is greatly appreciated.

Cheers.
Ethan