What all wagetypes in the standard payroll should have cumulation class 15 checked i.e. COA/CLA basis.
Assigning the Valuation of Averages to a Primary Wage Type.
Table to check
Table T51AV_P (Assignment of Wage Types to Average Calculation Rules)
only the NUM field contains a value, the operation VALBS (Evaluate Valuation Bases) queries whether a valuation basis has been entered in table T512W for the wage type. If this is the case, the wage type is valuated using the appropriate valuation basis. If a valuation basis has not been specified, but a specification has been entered for processing class 15,