"illegal attribute value"

Hello, 

sorry to disturb one more time, but I really can't understand why I have the
following problem.

I've EXACTLY followed the tutorial on how to setup virtual hosting in
Jigsaw. At step 8), when I hit the "commit" button after having changed the
general property "root name" to "virtual", I get the following error
message: 

org.w3c.tools.resources.IllegalAttributeAccess: Illegal attribute value
virtual
for org.w3c.jigsaw.root.name
        at org.w3c.jigsaw.config.PropertySet.setValue(PropertySet.java:85)
        at org.w3c.jigsaw.admin.BrokerFrame.remoteSetValues(Compiled Code)
        at org.w3c.jigsaw.admin.BrokerFrame.extended(Compiled Code)
        at org.w3c.jigsaw.frames.HTTPFrame.perform(Compiled Code)
        at org.w3c.tools.resources.FramedResource.performFrames(Compiled
Code)
        at org.w3c.tools.resources.FramedResource.perform(Compiled Code)
        at org.w3c.jigsaw.admin.AdminServer.perform(Compiled Code)
        at org.w3c.jigsaw.http.Client.processRequest(Compiled Code)
        at org.w3c.jigsaw.http.Client.startConnection(Compiled Code)
        at
org.w3c.jigsaw.http.socket.SocketClient.run(SocketClient.java:114)
        at org.w3c.util.CachedThread.run(Compiled Code)

I'm taking a look at the java files listed above but seems like it will take
me a lot of time to fix my problem...may someone help?

Thanks in advance, 

Mika
------------------------------------
Michalis Giannakopoulos 

99 rte d'Hermance
1245 Collonge-Bellerive
Switzerland