Error while reading Excel sheet using Java

I'm working with Spring/Hibernet using NetBeans 6.9.1. I'm trying to read an Excel file (.xlsx- Office 2007). The code for reading an Excel file is as follows using a Vactor to store data from the Excel sheet.

import java.io.FileInputStream;
import java.util.Iterator;
import java.util.Vector;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import model.NewHibernateUtil;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.hibernate.Session;
import org.springframework.validation.BindException;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.SimpleFormController;

private Vector importExcelSheet(ModelAndView mv)
{
    Vector cellVectorHolder = new Vector();
    try
    {         
        HSSFWorkbook myWorkBook = new HSSFWorkbook(new POIFSFileSystem(new FileInputStream("E:/Project/SpringHibernet/MultiplexTicketBookingNew/web/excelSheets/Country.xlsx")));
        HSSFSheet mySheet = myWorkBook.getSheetAt(0);
        Iterator rowIter = mySheet.rowIterator();
        System.out.println(mySheet.getRow(1).getCell(0));
        while(rowIter.hasNext())
        {
            HSSFRow myRow = (HSSFRow) rowIter.next();
            Iterator cellIter = myRow.cellIterator();
            Vector cellStoreVector=new Vector();
            while(cellIter.hasNext())
            {
                HSSFCell myCell = (HSSFCell) cellIter.next();
                cellStoreVector.addElement(myCell);
            }
            cellVectorHolder.addElement(cellStoreVector);
        }
    }
    catch (Exception e)
    {
        mv.addObject("msg", e.getMessage());
    }
    return cellVectorHolder;
}

The following is a method in my Controller th