ThinkingSphinx Indexing Problem

Hi, I've just installed Thinking Sphinx per the Railscasts
instructions, and everything seems to have installed fine, but I can't
seem to get the indexer task to run:

I have a model called Place:

  define_index do
    indexes :name, :sortable => true
    indexes description
    has lat, lng, updated_at, created_at

But, when I try to index I get this:
$ rake thinking_sphinx:index
indexer --config /Users/avishai/nyapp/config/development.sphinx.conf --
Sphinx 0.9.8-release (r1371)
Copyright (c) 2001-2008, Andrew Aksyonoff

using config file '/Users/avishai/myapp/config/
indexing index 'place_core'...
ERROR: index 'place_core': sql_query_range: min_id='0': must be
positive 32/64-bit unsigned integer.
total 0 docs, 0 bytes
total 0.010 sec, 0.00 bytes/sec, 0.00 docs/sec
distributed index 'place' can not be directly indexed; skipping.

Anybody have any idea why this isn't working as advertised?