How to write SQL to generate XML output?

Hi! Gurus!

I am creating a check stub in Oracle Payroll and am having some problems with the XML generation while fetching the earnings and deductions. I have a dynamic table which fetches the earn and dedn details and am using the xmlagg to create an xml string of the the pay details. It works fine if the number of checks is less than 300. If the number of employees processed is more than 300 than the problem starts which throws a JAVA error "XML-0108: (Fatal Error) Start of root element expected". Appreciate your quick feedback and help. Thanks.

Vamsee