Problem running site-cookbooks with chef-solo

[Paul Battley <pbattley@gmail.com>]

I've put together a little package to let me bootstrap an EC2 machine
and install software using Chef; the repository is at

 http://github.com/threedaymonk/chef-ec2

My solo.rb contains the line

 cookbook_path ["/etc/chef/recipes/cookbooks",
"/etc/chef/recipes/site-cookbooks"]

but I can't get Chef to find any recipes I put in site-cookbooks. If I
create them in cookbooks, they work fine. Otherwise, it just says:

 Cannot find a cookbook named blah

I must be missing something straightforward, but I can't work out what
it is. What am I doing wrong?

Thanks,
Paul.