Overhead & is not defined

What causes this issue?

Overhead &V1& is not defined.

System Response

Overhead calculation with this costing sheet leads to a termination.

How to fix this error?

Create overhead &V1&.
RESET N1
Enter the missing overhead &V1& in the appropriate row in the costing
sheet.
Select "Overhead" to branch to the detail screen for overhead
maintenance.

Error message extract from SAP system. Copyright SAP SE.