DataTable model doesn't get updated when <rich:datascroller> used.

    RichFaces FAQRichFaces Components FAQData Iteration Components FAQ

         If you have editable <rich:dataTable> and want to use pagging with <rich:datascroller> you should remember that datascroller component has ajaxSingle property set to true by default (Opposite to core components which has this property set to false by default).

         So the component not process the data on the page when switching the table page. In order to process your changes just redefine the ajaxSingle property with false value.