Rake Error on Coupa Express Install - undefined method `last' for {"login_engine"=>:environment}:Hash

[dspring0021]

I'm trying to install/deploy Coupa Express for the first time. After
doing a fresh install of all necessary packages and gems (and doing
the updates), I try to load the tables:
> rake db:schema:load
With rake v0.8.7, I keep getting the following error:
> undefined method `last' for {"login_engine"=>:environment}:Hash
And rake aborts.

If I uninstall v0.8.7 and reinstall v0.7.3, I get the following error:
> RubyGem version error: rake(0.7.3 not >= 0.8.3)

I'm kind of out of ideas here. I've been searching for solutions for
two days now and have no luck. Any help you can provide is much
appreciated. Thank you!

For your reference, here is my platform info:
<<<
Apache2, PHP5, MySQL5.1
Ruby1.8
--------------------
gem list:
actionmailer (2.3.5)
actionpack (2.3.5)
activerecord (2.3.5)
activeresource (2.3.5)
activesupport (2.3.5)
acts_as_ferret (0.4.4)
ferret (0.11.6)
rack (1.0.1)
rails (2.3.5)
rake (0.8.7, 0.7.3)
rtf (0.1.0)
vpim (0.695)
>>>

[dspring0021]

Resolved: I was missing the most recent installation guide which
clearly say to uninstall other version of rake. Thus:
> sudo gem uninstall rake -v 0.8.7

[dspring0021]

Sorry, to be more specific. I used the latest installation guide
available on SoureForge and installed all specific versions of the
gems. New gem list is:
<<<
actionmailer (1.3.3)
actionpack (1.13.3)
actionwebservice (1.2.3)
activerecord (1.15.3)
activesupport (1.4.2)
acts_as_ferret (0.4.1)
cgi_multipart_eof_fix (2.5.0)
daemons (1.0.10)
fastthread (1.0.7)
ferret (0.11.4)
gem_plugin (0.2.3)
mongrel (1.1.5)
mysql (2.8.1)
passenger (2.2.7)
rails (1.2.3)
rake (0.7.3)
rtf (0.1.0)
>>>

However, now I can launch the app, but I'm receiving a plethora of
runtime Ruby errors which I must now problem solve.