Solution : https://service.sap.com/sap/support/notes/102468 (SAP Service marketplace login required)
Key words : 
additional key words interval scales, time-dependent interval scales, quantity-dependent interval scales, message ve008 appears, attached advance correction, condition record exists, condition basis equals, scale base formula, interval scales, condition basis
Related Notes : 
       
| 167390 | Error message VT581 for maintennc of conditn types | 
| 139765 | Interval scales in the billing doc. w. Note 102468 | 
| 139660 | Interval scales in the billing document | 
| 122537 | Incor. dec. places during display of interv. scales | 
| 113526 | Rounding problem for interval scales |