QGeoMapObject's drawn in wrong place when using custom tile map projection

I'm trying to implement a custom tile based map plugin using Qt Mobility MAP API's.
I already have a custom tile map plugin that is based on QGeoTiledMapData, and it seems to work nicely when using Mercator map projection.

When I try to implement a different map projection there's some mysterious problem. I re-implemented these functions in my QGeoTiledMapData-derived class like the documentation suggests:
[CODE]
QPoint coordinateToWorldReferencePosition(const QGeoCoordinate &coordinate ) const;
QGeoCoordinate worldReferencePositionToCoordinate(const QPoint &pixel) const;
[/CODE]

Panning the map to correct location seems to work nicely. But when I try to add QGeoMapObject-based objects into the map, they are drawn in places where the default Mercator projection points instead of using my custom projection.

I have tested and double-checked my algorithms and they definitely work OK. So IMHO the custom map plugin should just work.

I tried with an example program, and it seems that the customized coordinateToWorldReferencePosition() -function is not even called for my QGeoMapObject object's coordinates (QCoordinate). If I understand correctly that should be done for each of the objects in order to determine where the objects should be placed on the map.

[B]
Any ideas where this goes wrong?
Is there need to implement/customize also some other functions in my custom map plugin in order for the objects to be placed correctly?
Or is there actually a bug in Qt Mobility regarding custom map projections?
[/B]