@parry2k thanks for this and I understand the logic, yet I don't get the number I'm looking for. I had expected to see for example for May 31 2019 a value of 21798. I do see this back in your graphs, but when I apply the same measure which you suggest, I still get the value of the sum of all values over the month in question. I cannot find what I've done differently than your solution.
Additional question I have is: if I were to have several type of 'parameters' in that field, so not just the one listed in my example, how would I write the filter to show only one? I tried applying filter(table, table[parameter]="selected paratemer" to the function, but am getting error message.
can you please look into this once again/ more? Below is the measure I've applied and I'm still getting the sum over all days in the month, rather than only the sum of the value of the last day of the month.
also, can you please advise how I would apply a filter? My table contains different categories in the same column and I'd need to be able to select on a specific on for my visuals.