Some polygons disappear when zooming in

[Tero Alén]

Hi

We have vector layer which contains polygons. These polygons are  
buildings on the map. When I zoom in some buildings disappear. Layer  
definition on mapfile looks like following.

	LAYER
		NAME rakennus
		TYPE POLYGON
		STATUS OFF
		CONNECTIONTYPE OGR
		CONNECTION "/var/www/tero/data/vector/rakennukset_alue.TAB"
		STYLEITEM "AUTO"
		CLASS
			NAME "rakennus"
		END
	END # Layer rakennus ends

I have no idea why buildings disappear. Is this some bug or what?

-Tero