Get last date per element in another dimension

[pat_ijp]

I have got a cube in TM1. Now I like to have the maximum of the dates dimension (Dates_solved) per element in the location dimension (Locations) where the measure Quantity is not null.

I have tried a couple of things, but these things doesn't work.

1. Properties Detail / Summary aggregation of the data item. --> No error, but makes no difference.
2. Maximum function in data item. --> Error, maximum is invalid in data item 'Date' of query 'Query1', expected one of the following types: 'value'
3. tail(filter(members([ops_Incidentmanagement].[Dates_solved].[Dates_solved].[Date]), [Quantity] > 0)) --> No error, but the result is a list with only the locations that have a measure quantity on the last date.

I think I have to work further on point 3. But I can't get the right result.