title: Rails - WARNING: Can't mass-assign protected attributes
body: <p>Continuing from here: <a href="https://stackoverflow.com/questions/6058486/rails-form-problems">Rails - Form problems</a>, everytime I try to create a new <code>group_membership</code> I get this: <code>WARNING: Can't mass-assign protected attributes: group, member</code> at my log and the ID's are added blank. </p>
  
  <p>Have been making changes to the <code>attr_accessible</code> of my models but so far no solution.</p>
  
  <p>Thanks in advance.</p>