I am trying to add a filter to sale.order tree view:

(record id="sale_tree_search_ext" model="ir.ui.view")    
(field name="name")sale_tree_search_ext.filter(/field)    
(field name="model")sale.order(/field)    
(field name="type")search(/field)    
(field name="inherit_id" ref="sale.sale_order_view_search_inherit_quotation" /)    
(field name="arch" type="xml")        
(xpath expr="/search/filter[1]" position="after")            
(filter name="has_special_status" string="has_special_status" domain="[('has_special_status','=',1)]" /)        
(/xpath)    
(/field)
(/record)

But I get this error:

Unknown field "sale.order.my_activity_date_deadline" in domain of < filter name="activities_overdue" > "[('my_activity_date_deadline', ')', context_today().strftime('%Y-%m-%d'))]"
Thank you