Find last entry in an array based on 1 criteria

In the attached example, I am trying to find the last entry for Batch# in Column O based on the Part# stored as text in Column D. I used the following formula [=IF(ISERROR(VLOOKUP((D7 & ""),$D$6:$O6,12,FALSE)),"",(VLOOKUP((D7 & ""),$D$6:$O6,12,FALSE)))], and it returns the first occurrence for any given Part# which is not what I need. I certainly appreciate any help you may be able to give!