Right alignment and tabs

I've imported a document that contains a table. I tried to widen a column and right-align some numerics, but couldn't get it to work. I see the <0> symbol, but it doesn't behave the way I would expect. In fact, they did nothing at all unless I clicked the "x", in which case I could never get the column to reappear. Not at all intuitive or helpful.

My environment is Mac OS X 10.5.2 in Firefox.
bocabo