Trying to impliment the Rails Flickr screen cast

I am trying to experiment with Flickr so I am following the screen
cast on the Rails web site.

I have installed the flickr gem and got an API key from flickr. I am
having an issue when I try to run the example though as I am told that
my API key has expired. As I only got it about 20 minutes before
writing this I find that hard to take.

Here is a copy of the error message.

Showing app/views/flickr/_photo.rhtml where line #1 raised:
Invalid API Key (Key has expired)
Extracted source (around line #1):
1: <img class="photo" src=<%= photo.sizes[0]['source'] %>">

app/controllers/flickr_controller.rb:5:in `search'

Has anybody got any Ideas as to what the problem is?