title: play framework unable to run an existing project
body: <p>I'm a rookie developer trying to run an application using play framework. I've followed the tutorial and can successfully create a new project. </p>
  
  <p>However when I go to the directory that has the project I'm supposed to work on and enter the play command I get the following error:</p>
  
  <pre><code>[error] Not a valid command: play (similar: last, alias, loadp)
  [error] Not a valid project ID: play
  [error] Not a valid configuration: play
  [error] Not a valid key: play (similar: clean)
  [error] play
  </code></pre>
  
  <p>I have very little knowledge regarding the framework and don't know where to start correcting my mistake. Any suggestions ?</p>