SAP Message TU408 - Alternative portion has different end of billing period

Diagnosis
You have entered an alternative portion. The end of this portion'sbilling period is &V2&.
The meter reading unit in the installation refers to the portion &v3&,with the end &v4&.
The new checksfor the alternative portion do not allow the end dates todiffer. If the end dates were to differ, you could not guarantee thecorrect determination of the schedule record.