acts-as-readable rails plugin issue

i'm controlling intridea's acts readable rails plugin messaging component i'm now building.
i've tangible summary category accordingly:

class post < activerecord::base
  acts-as-readable
end

and all seems operative according plan, nonetheless perplexing app arrangement unread messages summary view, i run problems.

their example: (i've altered underscores hyphens due formatting issues)

bob = user.find_by_name("bob")

bob.readings                      # => []

post.find_unread_by(bob)          # => [<post 1>,<post 2>,<post 3>...]
post.find_read_by(bob)            # => []

post.find(1).read_by?(bob)        # => false
post.find(1).read_by!(bob)        # => <reading 1>
post.find(1).read_by?(bob)        # => true
post.find(1).users_who_read       # => [<user bob>]

post.find_unread_by(bob)          # => [<post 2>,<post 3>...]
post.find_read_by(bob)            # => [<post 1>]

bob.readings                      # => [<reading 1>]

so seems i wanted list array unread messages sitting mailbox (for instance inbox (39) ), i should means something like:

<%= post.find_unread_by(current-user).count %>

but avail. i always seem stranded rudimentary perspective issues after everything's set.
any ideas?