Exception Error retrieving field value from bean

Dear All,

Can anyone help me regarding the following,

I am using java,jasper, Hibernate and mysql. I am generating a pdf report using the same technology. I need to pass multiple sql queries to JRBeanCollectionDataSource. for these i am using arraylist for each query after these am adding all lists into single, that list (list of lists) to JRBeanCollectionDataSource. i can access only one class details, but accessing another class details am getting the above exception. Solution required for this. Thanks in advance

Regards

Nagaraja