Invoice document will be negative

What causes this issue?

When calculating the debit data, the debit amount became negative (&V1&
&V2&).
This may be due to the following:
If you entered an invoice
The total amounts for the items credited is greater than the total
amounts for the items debited, which would lead to a credit memo rather
than an invoice.
If you entered a credit memo
The total amounts for the items debited is greater than the total
amounts for the items credited, which would lead to an invoice.

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?

Check whether you entered an invoice or a credit memo.
If you
entered a credit memo instead of an invoice
entered an invoice instead of a credit memo
enter the invoice/credit memo again.
Check the allocation criteria and make any necessary corrections.
Check that the invoice/credit memo indicator for deliveries and for
returns has been set properly.
IF &[SWITCH]MM_SFWS_CI_3& = 'X'.
Check whether this is a differential invoice or a final invoice in
<DS:GLOS.4C2A1925E72744D1E10000000A421947>Differential Invoicing</>, and
set the differential posting to <LS>As Credit Memo</> or <LS>As Invoice
</> as appropriate.
ENDIF.

Error message extract from SAP system. Copyright SAP SE.