Polygon information missing

Hello,

I am trying to obtain the polygon points from lat/lon coordinates of different buildings.

I have set up a Nominatim server with a map of Amsterdam (extracted from the geofabrik map of The Netherlands "Netherlands-latest.osm.pbf"). When I do polygon queries in most cases I do not get polygon information in the response. The same happens on the Nominatim Openstreetmap server. Example request: http://nominatim.openstreetmap.org/reverse.php?format=xml&lat=52.373912&lon=4.891633&zoom=18&polygon_svg=1&viewbox=

Also, I tried doing reverse search to obtain the street and number of a particular location and then use forward search but in most cases I did not get street and number in the results of the reverse search.

Am I doing something wrong with the request or should I import the database in a special way to support polygon-related requests?

Or is it possible that the region of Amsterdam center does not contain polygon information... I can see that a lot of requests for addresses in Ghent for example retrieve polygon info.

Thank you!