Error marshalling java.lang.Object - Variable arguments support

I'm in trouble. The "Marshalling Exception" was occured.

detail exception messages are this :
org.directwebremoting.extend.MarshallException: Error marshalling java.lang.Object: No converter found for 'class java.lang.Object'. See the logs for more details.
        at org.directwebremoting.dwrp.DefaultConverterManager.convertInbound(DefaultConverterManager.java:147)
        at org.directwebremoting.convert.ArrayConverter.convertInbound(ArrayConverter.java:93)
        at org.directwebremoting.dwrp.DefaultConverterManager.convertInbound(DefaultConverterManager.java:159)
        at org.directwebremoting.dwrp.BaseCallMarshaller.marshallInbound(BaseCallMarshaller.java:155)

The java method that called by DWR is this :
    public static String format(String pattern, Object ... arguments) {
        MessageFormat temp = new MessageFormat(pattern);
        return temp.format(arguments);
    }
This method is included in java.text.MessageFormat.

javascript is this:
        var args = "Test";

        MessageFormat.format ("This is a {0}", args, {
            callback:function(data) {
                alert(data);
            }, errorHandling:function(message) { alert(message); }
        });

The "format" method in MessageFormat has two arguments. The one is "String pattern". The Other is "Object ... arguments". This error is occured at "Object ... arguments".

Maybe "Variable-length argument" make a problem in DWR, converting javascript object to Java object.

Doesn't DWR support the "Variable-length argument" of JDK 1.5? Is there anyone help me?