How to: Show Add-in User Interface Errors
By default, if an add-in attempts to manipulate the Microsoft Office user interface (UI) and fails, no error message is displayed. However, you can configure Microsoft Office applications to display messages for errors that relate to the UI. You can use these messages to help determine why a custom Ribbon does not appear, or why a Ribbon appears but no controls appear.
Applies to: The information in this topic applies to document-level projects and application-level projects for the following applications: Excel 2013 and Excel 2010; InfoPath 2013 and InfoPath 2010; Outlook 2013 and Outlook 2010; PowerPoint 2013 and PowerPoint 2010; Project 2013 and Project 2010; Visio 2013 and Visio 2010; Word 2013 and Word 2010. For more information, see Features Available by Office Application and Project Type.
To show add-in user interface errors
Start the application.
Click the File tab.
In the categories pane, click Advanced.
In the details pane, select Show add-in user interface errors, and then click OK.
For Outlook, the Show add-in user interface errors checkbox is located in the Developer section of the details pane. For other applications, the checkbox is located in the General section of the details pane.