Is it posted before?
comboBox1.ValueMember = "baId";
comboBox1.DisplayMember = "baName";
comboBox1.DataSource = list; //<--list of au
comboBox1.DataBindings.Add("SelectedItem", au, "baAddress");
this line cause a no session exception. I think it is affected by first 2 lines. Bindings codes need to access related attributes on au instead of the one in the list. Though this access seems not necessary with the 'list' already set.
The baAddress is an attribute on au with lazy load, itself is a class.
Equals(object obj) on class of baAddress, is overrided for binding the same obj.
Remove lazy load could be a choice. What other ideas?