Using Concat in a Set Analysis expression

[ZoeM]

Hi Community.

I am trying to create an expression that will allow me to pull in two strings into one cell in a Pivot Chart to get my desired result, as the below:

String 1, String 2

I would like to pull in two items into one cell in a Chart Pivot. I am using the Concat function as stated below:

Concat( Gateways,', ')

The formula is working as intended, but I have multiple gateways with multiple dates and I am looking for Gateways where:

Only( {$<[Date Type]={'VPP Dates'}>}Gateways) 

I am assuming that a Set Analysis expression will help me resolve these two parameters. I have searched the blogs, but I cannot seem to find one that fits this situation. 

I built the below, but I am getting a set modification error:

Only({$<[Date Type]={'VPP Dates'},Concat(DISTINCT Gateways,',') >}Gateways)

Any help rendered to try and get this to work will be truly appreciated. 

Thanks Community

[Gysbert_Wassenaar · Accepted solution]

Concat is an aggregation function just as the Only function is. So you can use set analysis in the concat function too: Concat( {$<[Date Type]={'VPP Dates'}>} DISTINCT Gateways,',') 

[ZoeM]

Explains why you are an MVP! 

Your explanation works like a charm, and I appreciate the quick response