Theme Builder

I'm just started work on trying to use Theme Builder to change the Dashboard but fell at the first hurdle.

In "Manage Layouts" I created a new layout from the default one called TGBP. I then selected the new layout and in the Resources tab I selected dashboard.wiki and edited it; I simply added some text and saved it. Then I selected Builder Administration and selected the "Manage Spaces" tab and set the layout for all spaces (including the  (GLOBAL) of type dashboard space to the one I created ie, TGBP.

However when I select the dashboard the text I added to the layout is not displayed, so it doesn't look like the dashboard.wiki that I edited is being displayed. What have I missed or got wrong?

Ta,
Paul