flex.messaging.MessageException: Argument i

[salem_b_a]

I'm getting a strange serialization issue with flex blazeds Spring.
I can search, add and alter entities but when trying to delete i'm getting this error:

flex.messaging.MessageException: Argument is not an array

However when i try the debug mode on server(apache tomcat 6) everything is fine.
here the stack trace for BlazeDs:

[BlazeDS]Exception when invoking service 'remoting-service': flex.messaging.MessageException: Argument is not an array
  incomingMessage: Flex Message (flex.messaging.messages.RemotingMessage)
    operation = supprimer
    clientId = EA1F8D9C-BD0C-941A-F168-02A08E454F43
    destination = ClientService
    messageId = F8D2B72B-C1D3-E4C5-CB06-11AA332A95B8
    timestamp = 1301671457890
    timeToLive = 0
    body = null
    hdr(DSId) = EA1E7EDA-C60E-F245-CF47-35D38F0ED6FB
    hdr(DSEndpoint) = my-amf
  Exception: flex.messaging.MessageException: Argument is not an array
at flex.messaging.services.RemotingService.serviceMessage(RemotingService.java:225)
at flex.messaging.MessageBroker.routeMessageToService(MessageBroker.java:1503)
at flex.messaging.endpoints.AbstractEndpoint.serviceMessage(AbstractEndpoint.java:884)
at flex.messaging.endpoints.amf.MessageBrokerFilter.invoke(MessageBrokerFilter.java:121)
at flex.messaging.endpoints.amf.LegacyFilter.invoke(LegacyFilter.java:158)
at flex.messaging.endpoints.amf.SessionFilter.invoke(SessionFilter.java:44)
at flex.messaging.endpoints.amf.BatchProcessFilter.invoke(BatchProcessFilter.java:67)
at flex.messaging.endpoints.amf.SerializationFilter.invoke(SerializationFilter.java:146)
at flex.messaging.endpoints.BaseHTTPEndpoint.service(BaseHTTPEndpoint.java:278)
at org.springframework.flex.messaging.servlet.MessageBrokerHandlerAdapter.handle(MessageBrokerHandlerAdapter.java:79)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:647)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:563)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
...
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalArgumentException: Argument is not an array
at java.lang.reflect.Array.getLength(Native Method)
at flex.messaging.io.amf.translator.decoder.CollectionDecoder.decodeCollection(CollectionDecoder.java:155)
at flex.messaging.io.amf.translator.decoder.CollectionDecoder.decodeObject(CollectionDecoder.java:139)
at flex.messaging.io.amf.translator.decoder.ActionScriptDecoder.decodeObject(ActionScriptDecoder.java:70)
at flex.messaging.io.amf.translator.ASTranslator.convert(ASTranslator.java:77)
at flex.messaging.io.Java15TypeMarshaller.convert(Java15TypeMarshaller.java:71)
at flex.messaging.util.MethodMatcher.convertParams(MethodMatcher.java:211)
at flex.messaging.util.MethodMatcher.getMethod(MethodMatcher.java:132)
at flex.messaging.services.remoting.adapters.JavaAdapter.invoke(JavaAdapter.java:420)
at flex.messaging.services.RemotingService.serviceMessage(RemotingService.java:183)
... 27 more

Thanks for help.