Access PostGIS Raster layer through mapserver

I am trying to use a cgi script calling mapserver to display a raster layer that is stored in a PostGIS database. However, only a blank white image is returned and I don't know where the problem is.

The request seems to go through, but here is an error in the postgres log that I don't understand and the result is a white image.

My questions are:

1. What does the error from the postgres server log mean (see below)?


2. How can I make sure the white image is not due to a misspecification of the map extent?


3. Is there something obvious that I am doing wrong?

---

Here is some more detailed info for this problem.

The mapserver request is:

http://someurl.com/mapserv.cgi?map=../../usr/maps/test.map&mode=map&layers=kahoo&

The error from the postgres server log:

ERROR:  column "o_column" does not exist at character 39
STATEMENT:  select o_table_name, overview_factor, o_column, o_table_schema from raster_overviews where r_table_schema = 'public' and r_table_name = 'kahoo' and r_column = 'rast'

From the mapserver log:

.632473 msDrawMap(): rendering using outputformat named png (AGG/PNG).
.632541 msDrawMap(): WMS/WFS set-up and query, 0.000s
.633883 msDrawRasterLayerLow(kahoo): entering.

.859561 msDrawMap(): Layer 0 (kahoo), 0.227s
.859588 msDrawMap(): Drawing Label Cache, 0.000s
.859594 msDrawMap() total time: 0.227s
.862701 msSaveImage(stdout) total time: 0.003s
.862751 mapserv request processing time (loadmap not incl.): 0.231s
.862759 msFreeMap(): freeing map at 0x266bc60.

The mapfile used is:

MAP
 CONFIG "MS_ERRORFILE" "../../tmp/ms_error.txt"

 DEBUG 5

 NAME "test"
 SIZE 218 152
 EXTENT 739335 2268075 7761335 2284075
 UNITS METERS
 STATUS ON
 PROJECTION
  "init=epsg:26704"
 END


 WEB
  METADATA
    "wms_title"           "WMS Demo Server"
    "wms_onlineresource"  "http://someurl.com/mapserv.cgi?map=../../usr/maps/test.map&"
    "wms_enable_reqest"   "*"
  END
 END

 LAYER

    NAME kahoo
    TYPE RASTER
    STATUS ON
    DATA "PG:host=*** port=*** dbname='***' user='***' password='***' schema='public' table='kahoo' mode='2'" 
    PROCESSING "NODATA=0"
    PROJECTION
       "init=epsg:26704"
    END
 END
END

Here are the versions I am using: mapserver-6.0.3, postgresql-9.1.6, postgis-2.0.1