Hi Niladri,
Please check the groupings you have defined for your configuration. The grouping mentioned in V_001P_All for substitution should be same as the grouping you used to create the substitution subtype.
I would recommend you to review your groupings in the universal tables mentioned below for all parameters:
V_001P_All - Personnel Subarea Grouping
V_503_All - Employee Subgroup Grouping
Thanks and regards,
Vivek Barnwal