I am trying to follow the example in the documentation, but it doesn't work. I have followed everything verbatim in Creating ColumnSets in the Designer part 1. In part 2, step 8:

 At this point we need to set the ColumnSet that we made as the default ColumnSet used by all of the nodes in the tree. In the Properties Window, expand the Override node and scroll down to the ColumnSet property. In the drop-down to the right of the ColumnSet property, select the ColumnSet that we made previously.

When I pull down the drop-down, I see {none}. The ColumnSet I created previously isn't there.

 What am I doing wrong?