<asp:MultiView ID="MultiView1" runat="server" ActiveViewIndex="0">
            <asp:View ID="Vista1" runat="server" OnActivate="AttivaVista1">
                <asp:Button ID="DatiCaller" runat="server" Text="Utente connesso" 
                        SkinID="Attuale" OnClick="DatiCaller_Click" />      
                <asp:Button ID="V1Macro" runat="server" Text="Utente Cercato" SkinID="Alternativa" 
                        CommandName="NextView" Visible="false" OnClick="V1Macro_Click" />          

MultiView1.SetActiveView(View1)

MultiView.SetActiveView Method  

Sets the specified View control to the active view within a MultiView control. 

Use this method to set a View control within a MultiView control as the active view. 
The View control that is set as the active view is rendered to the client. 

Using the SetActiveView method to programmatically set the active view allows the application to determine which View control to render to the client at run time based on criteria such as a user's identity and preferences.