SAP Message 6D152 - The valid-from date of the SU is not the start of a settlement period

Diagnosis You have assigned a settlement unit on &v1&. However, this valid-fromdate is not a valid period start because the settlement unit hassettlement variant &v2&. One example of a valid settlement period startdate would be &v3&. Procedure Assign the settlement unit as a participating settlement on a validdate, or change the settlement variant in the participating settlementunit. Note that all the settlement units assigned on a certain date asparticipating settlement units must have the same settlement variant.You can only make an assignment for the period start of the settlementvariant.