The top example won't work, as you can see, the quotes break up (so either escape the quotes with \ or use the squiggly brackets (whatever they\re called) at the beginning and end of the string: {" -- "} )

But really, they should work the same way.

From what I can figure out, the most likely cause for the text not appearing is that the label itself is too small for the text (so try resizing the label).