Error doing st_union in spatialite

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I have a multipolygon layer in which I want to dissolved based on a class column. The steps I'm doing are:

1. create table tc_2010_00567 (gid int primary key, tc_2010 text(32));
2. select addGeometryColumn('tc_2010_00567', 'the_geom', 4618, 'multipolygon');
3. insert into tc_2010_00567 (gid, tc_2010, the_geom) select NULL, tc_2010, st_union(geometry) from tc_2010_00567__pol group by tc_2010;

I can create the table and add the geometry column (steps 1 and 2) but step 3 gives me the error IntegrityError: tc_2010_00567.the_geom violates Geometry constraint [geom-type or SRID not allowed]

My input dataset has SRID:4618 The select part (in step 3) works and I can load it in QGis (using QspatiaLite). But the insert into part is not working. Any clues as to what could be wrong? I'm using QSpatiaLite from QGis 2.8.1 and SpatiaLilte 4.1.1



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