cartography - cartodb: cannot import csv with geojson column working with cartodb -

i uploaded shape file cartodb

then exported csv

now want load csv file (i'm studying how generate csv other sources)

i have geojson strng column info of geometry (a polygon)

then try update the_geom query this:

update paisprov2012 set the_geom = st_setsrid(st_geomfromgeojson(geojson),4326) 

and error:

error: geometry type (multipolygon) not match column type (point) 

so try with

alter table paisprov2012 alter column the_geom type polygon using the_geom::polygon 

but

error: cannot cast type geometry polygon 

any idea?

changing of column types didn't work in old versions of cartodb (and default column type when null point). first query should work fine now.

the second query fail because polygon trying isn't projected polygon.