Sender cannot take part in the transfer of planning data

What causes this issue?

The sender cannot participate in the plan data transfer. Only orders
and WBS elements with the following characteristics can participate:
RESET N1
The "Plan Integrated" indicator is not set in the sender's master
record.
The sender has revenues:
The "Revenue Postings" indicator is set in the order type, in Orders.
The "Billing Element" indicator is set in WBS Elements.
A results analysis key is entered in the sender's master record.
The sender is not an investment measure.

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 your entry.
If you wish to delete the "Plan Integrated" indicator, you can do so
for WBS elements and internal orders in the master data maintenance.
The system moves the indicator back from the project profile or the
order type, and proposes it when you create master data.

Error message extract from SAP system. Copyright SAP SE.