Extension load error help

[David Morgenthaler]

I'm writing an extension, and, when I attempt to load my extension
module I get the following:

>>> from SARCrates.BoomBox.SARGeom import _gridManager
Traceback (most recent call last):
  File "<interactive input>", line 1, in ?
SystemError: _PyImport_FixupExtension: module
SARCrates.BoomBox.SARGeom._gridManager not loaded
>>>

Any ideas on what I did to cause this?
[PS -- I'm running Py2.1 on WinNT]

Thanks in advance,
David M.