Routable garmin maps using mkgmap

I have succeeded in generating very nice routable Garmin IMG files for Central Asia with mkgmap. When I try to use the same style sheets, only slightly modified, for Russia, neither BaseCamp nor my Garmin nuvi GPS can find street addresses, and streets (highway=*) are identified in BaseCamp as airport runways. Has anyone else faced a similar problem, and does anyone have any thoughts on how I should troubleshoot this?