Costing variant not for std cost est or mask costing variant

SAP Gurus,

We are getting the below error while assigning 3 different cost component structure to 3 different plants using 1 costing variant in Transaction Code OKTZ ' Assignment Org Units - Cost Component Structure'.

Choose costing variant not for std cost est or mask costing variant

Message no. KQ446

Diagnosis

The costing variant you entered is reserved for the standard cost estimate.

System Response

The standard cost estimate is always assigned to a cost component structure using masked entries for the plant and costing variant. All other costing variants can be assigned specifically.

Within a company code, standard cost estimates are saved under a single cost component structure. The cost component structure is found in the system under a masked plant and a masked costing variant.

Cost estimates other than standard cost estimates can be saved within the individual plants under different cost component structures. In this case, costing variants that are not for the standard cost estimate can be entered and assigned to a specific cost component structure.

Procedure

Enter a costing variant that is not for the standard cost estimate, or mask your entry for the costing variant. If you mask your entry for the costing variant, you must also mask your entry for the plant.

Your expert advice will be highly appreciated.

Regards,

Yousuf