I am trying to use variables in my modules manifest.pp with little luck

class mysoftware($version="dev-2011.02.04b") {
  File {
    links => follow
  }

  file { "/opt/mysoftware":
    ensure => directory
  }
  file { "/opt/mysoftware/share":
    source => "puppet://puppet/mysoftware/air/$version",
    recurse => "true",
  }
  }

This does not seem to be working when I assign this to a node via the nodes.pp file.

I am running puppetmaster 2.6.4 puppetd clients are 0.25