topology toolbar not active

Hello

Some weeks ago I created a geodatabase topology, validated it, got a list of all the errors in the error inspector window and an entry for the topology errors in the TOC.

Now I created some new features (with topology-errors) and wanted to validate the topology for them as well. But the topology toolbar is not active. So I tried it with the topology toolbox. This works (with warning 00059: Area validated is empty) and the errors are shown in the Map window. However, as the topology toolbar is not active, I can't open an error inspector window.

What do I have to do to activate the toolbar? (I'm using ArcMap 10.1, advanced)

Thanks in advance
Vera