title: Issues running Airflow DAG
body: <p>I have been working on Apache Airflow for a while now to schedule my workflow. I seem to be having issues scheduling my DAG. I have been using this SO question for reference : <a href="https://stackoverflow.com/questions/33126159/airflow-not-scheduling-correctly-python?rq=1">Airflow not scheduling Correctly Python</a></p>
  
  <pre><code>from airflow import DAG 
  from airflow.operators.bash_operator import BashOperator
  from datetime import datetime
  from datetime import timedelta
  
  default_args = {
      'owner': 'airflow',
      'depends_on_past': False,
  'start_date': datetime.now() - timedelta(minutes=5),
  'email': ['airflow@airflow.com'],
  'email_on_failure': False,
  'email_on_retry': False,
  'retries': 1,
  'retry_delay': timedelta(minutes=5),
  }
  
   dag = DAG('dag_mkdir_folder', default_args=default_args,
        schedule_interval=timedelta(minutes=5))
  
  
   task_hello = BashOperator(task_id='print_hello',
                        bash_command='mkdir test_airflow', dag=dag)
  </code></pre>
  
  <p>I'm trying to run the task using the following list of commands :</p>
  
  <pre><code> airflow scheduler
   airflow trigger_dag dag_mkdir_folder
  </code></pre>
  
  <p>I keep getting this as an error :</p>
  
  <pre>
  [2017-05-15 13:49:06,688] {models.py:322} DagFileProcessor406 INFO -      Finding 'running' jobs without a recent heartbeat
  [2017-05-15 13:49:06,689] {models.py:328} DagFileProcessor406 INFO -   Failing jobs without heartbeat after 2017-05-15 13:44:06.689284
  </pre>
  
  <p>The bash command is just supposed to create a new directory. The test version works fine.</p>