Large document: Have i missed out anything???

Based on the documentation i hav specified the followig properties:
watt.server.tspace.location=D:\LargeDocTemp
watt.server.tspace.max=300000
watt.server.keepAliveTimeout=180000
tn.xml.xqlThreshold = 50
tn.BigDocThreshold = 100
But still the isLarge variable is coming as false…

Any thing have i missed out???