SerializationException on RPC call when providing List from store.getModifiedRecords

[mama]

Hi
I am working with editable grid and i need to pass modified store records through RPC service.
I am getting SerializationException on RPC call.

I am simply passing list to following method..

reEditorServiceAsync.setReportColumns(record,new AsyncCallback<List<ReportColumn>>()

It gives serializationException , I am struggling here since last 2 days , can any one please help me out?