New record of & not consistent with fixed period of following record

What causes this issue?

The selected validity period of the stock purchase plan &V1& overlaps
with the fixed reference period of a subsequent infotype record for the
same plan. Overlapping fixed periods for subsequent stock purchase
plans are only allowed under specific circumstances (see below)

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?

Make sure that the selected stock purchase plan fulfills one of the
following conditions:
The validity end date of the selected plan lies before the start of the
fixed period of the next record.
The start of the fixed period of the selected plan is not earlier than
the start date of the fixed period of the next record.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.