Automating Word2000

I've made an ActiveX dll, where IDTExtensibility2 inteface is implemented. During startup of the application, in method IDTExtensibility2_OnConnection I add a button to the command bar of the Word2000. When word is being shut down, in method IDTExtensibility2_OnDisconnection I delete this button. If I debug the program I can see that there is no more button at command bar.
BUT, if I unregister ActiveX dll and start Word2000 again, I can see the button at command bar, although this was deleted before. However the button is not alive (there is no awaited activity after clicking it).
Does anybody know, why is button still there and how can I make hime to disappear? (I do not mean manually to disappear, but programmaly).

Thank you.

malinrob