Java Client exception at save time

Dear list,

When creating a new objet with my Java Client, I have the following 
exception (_classForNumber(28) returned null) when saving.
Thanks in advance for any help.

Pierre


java.lang.IllegalStateException: _classForNumber(28) returned null
 at 
com.webobjects.eodistribution.common._EOReferenceRecordingCoder.decodeClass(_EOReferenceRecordingCoder.java:617)
 at 
com.webobjects.eodistribution.common._EOReferenceRecordingCoder.decodeObject(_EOReferenceRecordingCoder.java:543)
 at 
com.webobjects.foundation.NSDictionary.decodeObject(NSDictionary.java:759)
 at sun.reflect.GeneratedMethodAccessor18.invoke(Unknown Source)
 at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:324)
 at 
com.webobjects.eodistribution.common._EOReferenceRecordingCoder$_Decoder.decodeObject(_EOReferenceRecordingCoder.java:704)
 at 
com.webobjects.eodistribution.common._EOReferenceRecordingCoder.decodeObject(_EOReferenceRecordingCoder.java:551)
 at 
com.webobjects.eodistribution.common._EONotificationCarrier.decodeObject(_EONotificationCarrier.java:106)
 at sun.reflect.GeneratedMethodAccessor11.invoke(Unknown Source)
 at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:324)
 at 
com.webobjects.eodistribution.common._EOReferenceRecordingCoder$_Decoder.decodeObject(_EOReferenceRecordingCoder.java:704)
 at 
com.webobjects.eodistribution.common._EOReferenceRecordingCoder.decodeObject(_EOReferenceRecordingCoder.java:551)
 at 
com.webobjects.eodistribution.common._EOServerReturnValue.decodeObject(_EOServerReturnValue.java:62)
 at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
 at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:324)
 at 
com.webobjects.eodistribution.common._EOReferenceRecordingCoder$_Decoder.decodeObject(_EOReferenceRecordingCoder.java:704)
 at 
com.webobjects.eodistribution.common._EOReferenceRecordingCoder.decodeObject(_EOReferenceRecordingCoder.java:551)
 at 
com.webobjects.eodistribution.common._EOReferenceRecordingCoder.decodeObjects(_EOReferenceRecordingCoder.java:587)
 at com.webobjects.foundation.NSArray.decodeObject(NSArray.java:1272)
 at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
 at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:324)
 at 
com.webobjects.eodistribution.common._EOReferenceRecordingCoder$_Decoder.decodeObject(_EOReferenceRecordingCoder.java:704)
 at 
com.webobjects.eodistribution.common._EOReferenceRecordingCoder.decodeObject(_EOReferenceRecordingCoder.java:551)
 at 
com.webobjects.eodistribution.client.EOHTTPChannel._responseToMessage(EOHTTPChannel.java:533)
 at 
com.webobjects.eodistribution.client.EOHTTPChannel.responseToMessage(EOHTTPChannel.java:603)
 at 
com.webobjects.eodistribution.client.EODistributedObjectStore._send(EODistributedObjectStore.java:590)
 at 
com.webobjects.eodistribution.client.EODistributedObjectStore.saveChangesInEditingContext(EODistributedObjectStore.java:423)
 at 
com.webobjects.eocontrol.EOEditingContext.saveChanges(EOEditingContext.java:3121)