When you show someone a sample of code that is failing, you should
always show them *real* code. Doing otherwise merely confuses those
that are trying to help.
Furthermore, this sounds like a support question. Did you make an
effort to ask on the talk mailing list or on irc? Further replies to
this thread should probably be made to the rubyonrails-talk list.
On your actual issue, does your model descend from AR::B? If not then
you must define to_param to return the string url encoding for your
model.