Model inheritance problem


I've bumped into the following problem. I have two models, one
inheriting from another:

I use single table inheritance

When I render a view that includes


for a SpecificMessage object, it works fine once.
After that, when I try to render it for any object I get the error:

undefined method `reply_link' for #<SpecificMessage:0xb6813948>

That sounds like a weird Dependencies autoloading problem. There have
been a few people with those recently. In my experience they often
boil down to doing require 'xxx' when you should be doing
require_dependency 'xxx' or not requiring it at all.