c# - Null reference exception while Invoke on a WCF triggered event connected method -

please me out. stuck @ 1 situation wcf. working on client-server app, server exposes services through wcf duplex channel. whole mechanism built pub-sub pattern. server executes remote method in every client proxy connected , sends updated entity argument. client proxy raises event called updateentityevent. every client module subscribed event method called updatedata(entity ent) through every part of program gets new or updated objects. never had such problems until received such exception in 1 of modules, more specific situation not repeatable every client. 1 day occurred on 1 client station specific user, (if meaningful) has laptop i3 processor, when other clients work on "weaker" machines. error:

<log4j:event logger="client application" timestamp="1291132669957" level="info" thread="wcf layer"><log4j:message>user has started application , logged in success.</log4j:message>     <log4j:event logger="client application" timestamp="1291133884092" level="fatal" thread="11"><log4j:message>type:      source:      system.windows.forms     method:      system.object marshaledinvoke(system.windows.forms.control, system.delegate, system.object[], boolean)     mesage:      object reference not set instance of object.     stacktrace:         w system.windows.forms.control.marshaledinvoke(control caller, delegate method, object[] args, boolean synchronous)        w system.windows.forms.control.invoke(delegate method, object[] args)        w clientapplication.controls.rampdashboard.mytaskscontrol.updatedata(entity entity)        w clientdataprovider.dataprovider.updateentityhandler.invoke(entity value)        w clientdataprovider.dataprovider.updateentitythread(object obj) w c:\somedir\somefile.cs:row 380        w system.threading._threadpoolwaitcallback.waitcallback_context(object state)        w system.threading.executioncontext.run(executioncontext executioncontext, contextcallback callback, object state)        w system.threading._threadpoolwaitcallback.performwaitcallbackinternal(_threadpoolwaitcallback tpwaitcallback)        w system.threading._threadpoolwaitcallback.performwaitcallback(object state)     innerexception:       <log4j:throwable>system.nullreferenceexception: object reference not set instance of object.        w system.windows.forms.control.marshaledinvoke(control caller, delegate method, object[] args, boolean synchronous)        w system.windows.forms.control.invoke(delegate method, object[] args)        w clientapplication.controls.rampdashboard.mytaskscontrol.updatedata(entity entity)        w clientdataprovider.dataprovider.updateentityhandler.invoke(entity value)        w clientdataprovider.dataprovider.updateentitythread(object obj) w c:\somedir\somefile.cs:row 380        w system.threading._threadpoolwaitcallback.waitcallback_context(object state)        w system.threading.executioncontext.run(executioncontext executioncontext, contextcallback callback, object state)        w system.threading._threadpoolwaitcallback.performwaitcallbackinternal(_threadpoolwaitcallback tpwaitcallback)        w system.threading._threadpoolwaitcallback.performwaitcallback(object state)</log4j:throwable><log4j:locationinfo class="clientapplication.program" method="currentdomainunhandledexception" file="" line="0" /></log4j:event> 

the updatedata() method this:

private delegate void updatedatahandledelegate(entity entity);     /// <summary>     /// updates data.     /// </summary>     /// <param name="entity">the entity.</param>     private void updatedata(entity entity)     {         if (invokerequired)         {             invoke(new updatedatahandledelegate(updatedata), entity);         }         else         {                // business logic here         }     } 

additional info is, entity object control receives through updatedata provides data used fill commercial spreadsheet control. question is: causes error, null in entity object passed in updatedata or invoke problem. if so, how happen has null reference in invoke when updatedata subscribed update event earlier , never have chance triggered otherwise through subscribe procedure called in control's constructor long after initializecomponent ?? null here, if sth. inside entity object, wouldn't error have been more specific??

thank ideas