In Visual Basic, on the Add-Ins menu, click Add-In Manager.
In the Add-In Manager dialog box, select Visio UML Add-In. For Load Behavior, select Loaded/Unloaded and Load On Startup, and then click OK. The Visio UML Add-In toolbar appears.
Tip: When the Microsoft Visio UML Add-In creates the toolbar, it also adds commands to the Tools menu. You can locate the commands by clicking Visio UML Solution on the Tools menu.