SAP Message AO293 - Material group &1 was already used for the distribution - please correct

Diagnosis Material group &V1& was already used for percentage distribution. System Response You are not allowed to enter material group &V1& a second time. Procedure Check your entry. Instead of entering material group &V1& a second time, you shouldchange the existing entry for the percentage distribution to thismaterial group. Check the existing distribution to material group &V1&.