matlab com event interop exception

matlab registers com event and com callback. matlab local method success in my develop machine. there is an exception in com on other machine:

System.Reflection.TargetException: Object does not match target type.
   at System.RuntimeType.InvokeDispMethod(String name, BindingFlags invokeAttr, Object target, Object[] args, Boolean[] byrefModifiers, Int32 culture, String[] namedParameters)
   at System.RuntimeType.InvokeMember(String name, BindingFlags bindingFlags, Binder binder, Object target, Object[] providedArgs, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParams)
   at System.RuntimeType.ForwardCallToInvokeMember(String memberName, BindingFlags flags, Object target, Int32[] aWrapperTypes, MessageData& msgData)
   at InQuant.Strategy.IStrategyEvent.OnEvent(String eventMsg)

[liusi sun]

matlab event register:
registerevent(obj.service,{'OnEvent',@obj.ProcessEvent});
matlab callback methon:
function ProcessEvent(obj,varargin)
            eventMsg=varargin{3};
            if isnan(eventMsg)
                return;
            end       
        end

c# COM event:
[ComVisible(false)]
    public delegate void OnEventDelegate(string eventMsg);

    public event OnEventDelegate OnEvent;

exception position:
if (this.OnEvent != null)
                    {
                        this.OnEvent(eventMsg);
                    }