Item & cannot be posted to (retained earnings)

What causes this issue?

The FS item to be posted is not permitted since it is an item, which is
posted automatically by the program.
Such items are <GL:retained_earnings>retained earnings</> on the
balance sheet and income statement and are referred to as
<GL:selected_item>selected FS items.</>

System Response

Error message

How to fix this error?

Choose a FS item other than retained earnings.

Error message extract from SAP system. Copyright SAP SE.