Ruby soundcloud Gem : uninitialized constant SoundCloud (NameError)

Ruby soundcloud Gem : uninitialized constant SoundCloud (NameError)

I installed the SoundCloud ruby gem but when I tried running the example
'Print links of the 10 hottest tracks' on this page
https://github.com/soundcloud/soundcloud-ruby I kept getting an error
message "uninitialized constant SoundCloud (NameError)"
I did follow the instruction on the example, registered a client and got
my client_id (not sure how to get the access token, which is not required
in this example)
I followed the instruction on http://docs.rubygems.org/read/chapter/3 to
add require 'soundcloud' to the example code but i still keep getting the
same error message.
I am using OSX terminal.
sorry i'm new to ruby and soundcloud API so my question might be very
entry level.