Reversal is not possible for the selected entry

What causes this issue?

No reversal was carried out for the selected entry. This may be due to
the following:
The meter reading result has been billed
All billing orders of this entry have been allocated billing documents
that have been reversed for adjustment. This is the case if there is an
entry in the field for the document number of the adjustment reversal in
the detial display for billing orders.
After making a selection using a device, you attempted to delete a
billing order. However, this billing order is still allocated to other
devices.
Specially reversed billing documents for the primary installation of an
installation group are allocated to all billing orders for this entry.
IF &[SWITCH]ISU_LOC_CI_EHP4& = 'X'
On-site billing has taken place for the meter reading results. You
cannot delete the meter reading results.
On-site billing is scheduled for these meter reading orders. You cannot
delete the meter reading orders.
ENDIF.
If this is not the case, then there may be data inconsistencies that
require analysis.

System Response

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

How to fix this error?

Proceed as follows:
If the meter reading result has already been billed, first reverse the
corresponding billing with transaction <DS:TRAN.EA20>Delete Adj.
Reversal frm Bill. Order</>.
If specially reversed billing documents have been allocated to all the
billing orders for the item, use transaction <DS:TRAN.EA24>Delete doc.
no. of adjustment reversal from billing order</> to release the bililng
orders for reversal.

Error message extract from SAP system. Copyright SAP SE.