I think since you are using older Aspose.Excel version, kidly try the latest version (Aspose.Cells)
For your info Aspose.Excel has been renamed to become Aspose.Cells now which is more reliable, stable than before and prosperous with enhanced and advanced functionality. There is not much labour required while upgrading to the newer Aspose.Cells. When you ugrade to the newer Aspose.Cells, Please note: Some APIs (classes, struct, enumerations) are added based on some advanced features that we offer, the previous classes (with their members) are retained and optimised but a few classes are renamed, some additional members (properties, methods etc.) are also included of the classes.
Following is the classes list which are renamed:
1. Excel class is replaced by Workbook class.
2. ExcelDesigner class is replaced by WorkbookDesigner class.
3. ExcelHelper class is replaced by CellsHelper class.
And for more info, please check the APIs: http://www.aspose.com/Products/Aspose.Cells/Api/ and Programmer's guide: http://www.aspose.com/Wiki/Default.aspx/Aspose.Cells/