Solution : https://service.sap.com/sap/support/notes/1113840 (SAP Service marketplace login required)
Key words : 
defining time-dependent depreciation terms, time-dependent valuation parameters, enterprise extension ea-fin, time-dependent depreciation terms, previous depreciation terms, release sap erp 6, rules generally apply, check entries carefully, field t090na-xdaily, make clear entries
Related Notes : 
       
| 1631038 | Switching to depreciation key with fewer depreciation types | 
| 1451307 | Restrictions when using time-dependent depreciation terms | 
| 1266394 | FGV 002 when maintaining time-dependent depreciation terms | 
| 1121965 | Documentation Enterprise Extension EA-FIN | 
| 981222 | FAQ: Time-dependent valuation parameters | 
| 965032 | Differences between old and new depreciation calculation |