Puppet could not find class roles::webserver

I'm trying to get classes working in puppet, but it gives me an error when I try puppet agent -t on the node:

root@webserver01:/etc# puppet agent -t

Info: Retrieving plugin
Error: Could not retrieve catalog from remote server: Error 400 on SERVER: Could not find class roles::webserver for localhost on node localhost
Warning: Not using cache on failed catalog
Error: Could not retrieve catalog; skipping run

note: I edited the localhost parts above. I have the following site.pp:

root@puppet:/etc/puppet/manifests# cat site.pp 
node 'default' {
}

node 'webserver01' {

include roles::webserver

file {'/etc/test':
  ensure  => file,
  owner   => 'root',
  group   => 'root',
  mode    => '0644',
  content => 'df',
}

}

the modulepath:

root@puppet:/etc/puppet/manifests# puppet config print modulepath
Warning: Setting templatedir is deprecated. See http://links.puppetlabs.com/env-settings-deprecations
(at /usr/lib/ruby/vendor_ruby/puppet/settings.rb:1139:in `issue_deprecation_warning')
/etc/puppet/modules:/usr/share/puppet/modules

the modules dir:

root@puppet:/etc/puppet/modules# tree --charset=ASCII
.
|-- roles
|   `-- webserver
|       |-- files
|       |-- manifests
|       |   `-- init.pp
|       `-- templates

and the webserver class:

root@puppet:/etc/puppet/modules/webserver/manifests# cat init.pp
class webserver {
package { apache2:
ensure => present,
}

notify {"in webserver class": }

file {'/etc/test2':
ensure  => file,
owner   => 'root',
group   => 'root',
mode    => '0644',
content => 'df',
}
}

It works fine if I have the module in /etc/puppet/modules/webserver (removing the roles part), but it keeps failing when I try it with the roles directory. It still fails if I rename init.pp to webserver.pp. Can someone help?