Complete allocation structure &

What causes this issue?

During settlement, the system puts the sender debits into groups
(assignments), which are settled using the same settlement cost
element. The settlement assignment is made in the allocation structure,
which is stored in the settlement rule for the sender (under settlement
parameters).
Cost element &V2& cannot be assigned to a settlement cost assignment in
allocation structure &V1&, and therefore it cannot be assigned to a
settlement cost element.

How to fix this error?

Possible solutions are as follows:
If the posting under cost element &V2& was made to the sender because
of an incorrect entry, and you can reverse the posting, and do not need
to update the allocation structure. You only need to reverse the
incorrectly assigned posting before repeating the settlement.
Exception: For an investment measure with a line item settlement, you
need to extend the allocation structure, even after the reversal.
If the posting was made correctly, you can do the following:
You can assign a different allocation structure to the sender: In the
master data maintenance for the sender, choose "Settlement rule -> Goto
-> Settlement parameters" and then enter a different allocation
structure.
If necessary, also check whether the correct allocation structure is
entered in the settlement profile. The allocation structure is
defaulted in the settlement profile when you create sender master data
or when you maintain the settlement rule.
You can update allocation structure &V1&

Error message extract from SAP system. Copyright SAP SE.