silverlight 4 not work in firefox and chrome

I create Silverlight WCF RIA application. I use Entity Framework 4 for data access.

I test my application on IE 8 and it work fine but when I test on Firefox 4 or Chrome 10 I got Exception when I call RIA service. (It got error even service that just return data)

I want to know, how can I make Silverlight 4 application work on IE, Firefox and Chrome?

Error:

-- Exception -->
Load operation failed for query 'GetData'. Exception of type 'System.ServiceModel.DomainServices.Client.DomainOperationException' was thrown.

-- stack -->
   at System.ServiceModel.DomainServices.Client.WebDomainClient`1.EndQueryCore(IAsyncResult asyncResult)
   at System.ServiceModel.DomainServices.Client.DomainClient.EndQuery(IAsyncResult asyncResult)
   at System.ServiceModel.DomainServices.Cli开发者_如何学JAVAent.DomainContext.CompleteLoad(IAsyncResult asyncResult)

As far as I can remember. This is a bug on Silverlight runtime. We called Microsoft for this case and they also said it is a bug and no more response. We decided to drop the support on Firefox and go only with IE.