You cannot plan cost element & on cost center & manually

What causes this issue?

The value of cost element &v1& has already been determined in cost
center &v2& using detailed planning. It is only possible to make
changes using data transfer if the data transfer is performed by
importing or copying another detailed planning session.

System Response

The planning record to be transferred is written to the error log.

How to fix this error?

If this message appears during revaluation, not the following: Plan
values that are created by detailed planning cannot be revaluated and
therefore remain unchanged. As detailed planning works on a
year-by-year basis, this error message will appear if you have not
selected all periods in a year for revaluation.

Error message extract from SAP system. Copyright SAP SE.