Help with Railroady

I did mange to install railroady, and when I do ‘rake diagram:all’ and
‘open
doc/*.svg’ I do see some diagrams, but no instance variables or
inheritance
connections.
When I do something like

‘railroady -i -o controller.png -c’ or ‘railroady -i -C | neato -Tpng >
controllers.png’ it generates a png that can’t be opened or a png that
is
just the same as before (without instance variables or inheritance)

Please help me

Thank you,
Rodrigo