DataTable LoadWorksheetInDataTable(string fileName, string sheetName)
{
	DataTable sheetData = new DataTable();
    using (OleDbConnection conn = this.returnConnection(fileName))
    {
    	conn.Open();
        // retrieve the data using data adapter
        OleDbDataAdapter sheetAdapter = new OleDbDataAdapter("select F2, F4 from [" + sheetName + "]", conn);
        sheetAdapter.Fill(sheetData);
	}
    return sheetData;
}