title: Concourse S3 resource can't find simple file; 'no versions available'
body: <p>I've got a Concourse trigger set to detect when a particular file appears in an S3 bucket. Using this resource: <a href="https://github.com/concourse/s3-resource" rel="nofollow noreferrer">https://github.com/concourse/s3-resource</a> . Configuration is like so:</p>
  
  <pre><code>- name: s3-trigger-file
    type: s3
    source:
        bucket: mybucket
        regexp: filename_that_doesnt_change
        access_key_id: {{s3-access-key-id}}
        secret_access_key: {{s3-secret-access-key}}
  </code></pre>
  
  <p>I use it as a trigger like so:</p>
  
  <pre><code>jobs:
    - name: job-waiting-for-s3-file-to-appear
      public: true
      plan:
      - get: s3-trigger-file
        trigger: true
  </code></pre>
  
  <p>Seems like an extremely simple configuration. However, when I start the job and put a file in the bucket, I get 'no versions available'. </p>
  
  <p><a href="https://i.stack.imgur.com/eZOyd.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/eZOyd.png" alt="enter image description here"></a></p>
  
  <p>Any suggestions on how I might proceed in troubleshooting? Thanks ~~</p>