Exception any clues what to look for?

Hi,

Any ideas where to begin looking, maybe you guys can help me where to look, 
what exactly does exception mean?

19  18.07.2006 16:15:46.187 1,000 SEVERE Thread[ULC Communication Controller 
Thread,6,main] com.ulcjava.base.client.UISession$k_ run exception occured 
[com.ulcjava.base.client.ConnectorException: error while sending requests
at 
com.ulcjava.base.development.DevelopmentConnector.sendRequests(DevelopmentConnector.java:5)
at com.ulcjava.base.client.UISession$k_.run(UISession$k_.java:79)
at java.lang.Thread.run(Thread.java:595)
Caused by: com.ulcjava.base.shared.internal.IllegalArgumentException: No 
coder registered for class 
ch.abacus.lib.ui.propertyinspector.display.DisplayProperty
at 
com.ulcjava.base.shared.internal.UlcObjectOutputStream.a(UlcObjectOutputStream.java:102)
at 
com.ulcjava.base.shared.internal.UlcObjectOutputStream.writeObject(UlcObjectOutputStream.java:19)
at 
com.ulcjava.base.shared.streamcoder.CollectionCoder.writeObject(CollectionCoder.java:19)
at 
com.ulcjava.base.shared.internal.UlcObjectOutputStream.writeObject(UlcObjectOutputStream.java:171)
at 
com.ulcjava.base.shared.internal.UlcObjectOutputStream.writeObject(UlcObjectOutputStream.java:72)
at com.ulcjava.base.shared.internal.Request.writeRequests(Request.java:0)
at 
com.ulcjava.base.development.DevelopmentConnector.a(DevelopmentConnector.java:9)
at 
com.ulcjava.base.development.DevelopmentConnector.sendRequests(DevelopmentConnector.java:16)
at com.ulcjava.base.client.UISession$k_.run(UISession$k_.java:79)
at java.lang.Thread.run(Thread.java:595)
]

Mario
Abacus Team