Rebol font size not working

For some reason, when I run my code - or even the example code from the Rebol site - the font size of the GUI text has no effect. I can write:

view layout [ text "This should be big!" font [size: 50] ]

      

        
        
        
      

    

or even:

view layout [ text "This should also be big!" font-size 50 ]

      

        
        
        
      

    

but do nothing. In particular, I can add color to the text.