No mode combinations have been deleted

What causes this issue?

You have selected one or more rows in the SNP plan display and have
chosen <LS>Delete Mode Combination</>.
Deletion is only possible in the following circumstances:
The row contains an SNP plan with an already maintained mode
combination that has not yet been generated
The row contains data for automatic SNP plan generation
No mode combination has been deleted because these prerequisites have
not been fulfilled by any of the selected rows.

System Response

The system was not able to delete a mode combination or input row.

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.