The selected Add-In has not been confirmed to be 'Command Line Safe', and may require some user intervention (possible UI).
This error generally occurs when an Add-in has been selected to be used from the Command prompt (DOS prompt) but the add-in does not list itself as safe for the command line. The add-in might display UI that could interfere with command line use.
To correct this error
From the Tools menu, choose Add-In Manager.
In the Add-In Manager dialog box, clear Command Line for the add-in.