Why is dataSource(String selectExpression) methos not called on my custom XML datasource

[ravigharshi]

Hi,

        I have a custom xml datasource based on STX XPATH processing. Need to understand why the dataSource(String selectExpression) method is not called on my datasource. DataSource expression in Main report is:

<dataSourceExpression><!CDATA[((net.sf.jasperreports.engine.data.JRXmlDataSource)$P{REPORT_DATA_SOURCE}).dataSource("Invoice/InvoiceLine")]]</dataSourceExpression>