Spatialite: use of virtual spatial index for distances

I'm currently learning to use spatial access methods for query optimization. I'm going through the examples in spatialite cookbook and got stuck in here http://www.gaia-gis.it/gaia-sins/spatialite-cookbook/html/pp-adjacent.html According to the tutorial, in order to find the pairs of populated places that their distance is pp2.id AND pp2.ROWID IN ( SELECT pkid FROM idx_populated_places_geometry WHERE pkid MATCH RTreeDistWithin( ST_X(pp1.geometry), ST_Y(pp1.geometry), 0.02)) ORDER BY 2; Which throws an error because of no longer use of geocallback functions RTree***. I checked the update on this and this has been substituted by the use of virtual spatial index. We have to use a subquery of the form SELECT ROWID FROM SpatialIndex WHERE f_table_name = AND search_frame = So i tested this SELECT pp1.name AS "PopulatedPlace #1", GeodesicLength(MakeLine(pp1.geometry, pp2.geometry)) AS "Distance (meters)", pp2.name AS "PopulatedPlace #2" FROM populated_places AS pp1, populated_places AS pp2 WHERE GeodesicLength( MakeLine(pp1.geometry, pp2.geometry)) pp2.id AND pp2.ROWID IN ( SELECT ROWID FROM SpatialIndex WHERE f_table_name ='populated_places' AND search_frame = pp1.geometry) ORDER BY 2; And the result set was awfully wrong PopulatedPlace #1 Distance (meters) PopulatedPlace #2 Ariano 0.000000 Ariano Campolongo Maggiore 0.000000 Campolongo Maggiore Campolongo Maggiore 0.000000 Campolongo Maggiore Campolongo Maggiore 0.000000 Campolongo Maggiore Campolongo Maggiore 0.000000 Campolongo Maggiore Campolongo Maggiore 0.000000 Campolongo Maggiore Campolongo Maggiore 0.000000 Campolongo Maggiore Ariano 0.000000 Ariano Could please someone explain this behavior and/or give an example of proper use of the virtual spatial index in order to obtain distance queries?