Rails - Jul 2005 - FlashHash and boolean values

If I put true or false boolean value into flash[''..''] nothing
will
render into my browser. Nothing.
But if I use 0, 1 or any other value it will work. And there''s no  
error, exception but rails silently fails. It''s on Mac OS X /  
WebRick / Rails latest (0.13.1).

I guess it should work in Ruby everything is object and there are no  
"inner types". So true and false are objects. What am I missing?

     Gábor