title: Django issue during migrations - lazy reference
body: <p>I currently added this model to my app</p>
  
  <pre><code>from mainApp.models import modelPatient
  
  class modelBodyParts(models.Model):
      part_name             = models.CharField(max_length=1000, unique=False , default="")
      modelPatient          = models.ForeignKey(modelPatient)
      result                = models.CharField(max_length=3000, unique=False , default="")
  </code></pre>
  
  <p>Now the makemigrations and migrate commands give me the following error</p>
  
  <pre><code> &gt;&gt;python manage.py makemigrations 
   &gt;&gt;python ./manage.py migrate
  
  ValueError: The field interviewApp.modelInterviewAnswers.patients was declared with a lazy reference to 'mainApp.modelpatients', but app 'mainApp' doesn't provide model 'modelpatients'
  </code></pre>
  
  <p>I am not sure what that means. But I do remember that at one point <code>mainApp.modelpatients</code> existed and then it was changed to <code>mainApp.modelpatient</code>
  which still exists.How do I resolve this issue and why is this showing up ? Any help would be appreciated.</p>