ANALYZE errors (postgres 8.1.4)

I'm having some problems with ANALYZE.

When I run ANALYZE on a postgis enabled database created by ogr2ogr from
the Census Bureau's tiger data I get the following error for a number of
the tables created:

tiger2005se=# ANALYZE arealandmarks ;
NOTICE: no notnull values, invalid stats

I can't find any reference to this error. What does it mean?

Table structure:
tiger2005se=# \d arealandmarks
Table "public.arealandmarks"
Column | Type | Modifiers
--------------+---------------+-----------------------------------------------------------------
ogc_fid | integer | not null default
nextval('arealandmarks_ogc_fid_seq'::regclass)
wkb_geometry | geometry |
module | character(8) |
file | character(5) |
state | numeric(2,0) |
county | numeric(3,0) |
cenid | character(5) |
polyid | numeric(10,0) |
land | numeric(10,0) |
Indexes:
"indx_mod_arealandmarks" btree (module)
Check constraints:
"enforce_dims_wkb_geometry" CHECK (ndims(wkb_geometry) = 2)
"enforce_srid_wkb_geometry" CHECK (srid(wkb_geometry) = 32767)

Thanks,
Tim Bowden
Mapforge Geospatial