Limitations of Global Templates and Excel Add-ins (.xla Files)
Documents, workbooks, and templates might not work correctly as global templates or Excel add-ins (.xla files).
Applies to: The information in this topic applies to document-level projects for the following applications: Excel 2007 and Excel 2010; Word 2007 and Word 2010. For more information, see Features Available by Office Application and Project Type.
If a Microsoft Office Word template has managed code extensions, the project assembly is not called if the template is attached as a global template or loaded from the Startup directory of Word. In addition, the document does not recognize the format of a template that is part of an Office solution.
There is no Office project for creating an Excel add-in (.xla file). It is possible to save a workbook as an .xla file, but it is not a supported operation and is not recommended. If you save a workbook that has managed code extensions as a Microsoft Office Excel Add-In (*.xla) file, you can select it in the Add-Ins dialog box to apply to another workbook. In some cases your code will run in the target workbook after the add-in is applied, but such use of the Office solution is not supported.