I am working on Chap 8  of "Getting Started" (Titled "(Relations of Models)").
I have a One2many fields in a model named estate.estate as below:
offer_ids = fields.One2many('estate.property.offer', 'partner_id', string='Offers4')
In the co-model estate.property.offer I have a Many2one counterpart:
partner_id = fields.Many2one('res.partner', string='Property Offers', required=True) 
In the form view of the model estate.estate, I have the following XML data

	  
        estate.estate.form
        estate.estate
        
            
                
                    
                     
                    
                    
                     
                       
                       
                       
                       
                     
                     
                         
                             
		             
		                 
		                 
		                 
		                 
		                 
		                 
		                 
		                 
		                 
		                 
		             
                         
                         
		             
			          
		             
	                 
I get the correct display, but in the field where the One2many field offer_ids supposed to work,
when I hit "Add a line", I got the following exception:
Traceback (most recent call last):
  File "/home/albert/src/odoo/odoo/http.py", line 639, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/home/albert/src/odoo/odoo/http.py", line 315, in _handle_exception
    raise exception.with_traceback(None) from new_cause
ValueError: Invalid field 'Title' on model 'res.partner'
Where the co-called invalid field is the first field declaration in my XML file. When I mark out
that line, then the error message will show the next field as invalid on model 'res.partner'.
I think I had some mistakes on XML description. But I cannot find out after searching 
it for 5 hours.