Solution : https://service.sap.com/sap/support/notes/69880 (SAP Service marketplace login required)
Key words : 
additional key words vf11, extend function module pricing_copy, type    optionaltkomv              komvsource_komv        komv, interface table parameters/exceptions, prerequisites designalso refer, related note 76426 solution, table parameter    ref, cancel billing documents, error message time_out, billing items
Related Notes : 
       
| 151267 | VF188 - no cancellation of external billing docs. | 
| 143327 | Upgr.3.1I:Release of canclltn.returns message KI235 | 
| 119487 | Performance VF11: delivery-related billing | 
| 92575 | Cancellation cannot be transferred to FI | 
| 82194 | No statistics update when cancelling | 
| 80559 | VF02 : Rebate conditions are lost | 
| 76426 | Cancellation billing documents without items | 
| 65987 | Performance problems when cancelling with VF11 | 
| 53832 | Performance problems when cancelling |