SAP Message U7038 - Billing period &1 (meter reading &2) different to bill. period &3 (MR &4)

Diagnosis
The billing period &V1& in the meter reading result &V2&does not correspond to the billing period &V3& in the meterreading result &V4&. The meter reading results allocated to a billingorder must have the same billing period.
Unauthorized changes may have been made to the Customizing settings.

Procedure
Contact SAP to determine the cause of this error.