Generating emacs tags file for a Ruby on Rails project

I am generating a tags file for emacs for my Ruby on Rails project with the following command:

ctags -f TAGS --extra=-f --languages=-javascript --exclude=.git --exclude=log -e -R . $(rvm gemdir)/gems/

When I try to find tags (Using M-.) some tags are working fine, but with lots of other tags I get errors like:

tag-find-file-of-tag-noselect: File /Users/simao/Documents/sp/ofe/° ¡ not found

etags-goto-tag-location: Rerun etags: `^class Tools::FilteringSteps' not found in /Users/simao/Documents/sp/ofe/lib/geo_db.rb

How are you generating tags for your RoR projects with emacs? Did you ever see this problem before?

This is the output of ctags --version

Exuberant Ctags 5.8, Copyright (C) 1996-2009 Darren Hiebert
Compiled: Mar  9 2012, 15:47:35
Addresses: <dhiebert@users.sourceforge.net>, http://ctags.sourceforge.net
Optional compiled features: +wildcards, +regex

My emacs version:

GNU Emacs 24.0.95.1 (x86_64-apple-darwin, NS apple-appkit-1038.36) of 2012-04-02