API - Custom Dimensions with Multiples Sites


I have an issue when I use the Matomo API to retrieve Data.
It seems that I’m not able to get data when I specify a custom dimension and multiple sites at the same time.

For example, this URL works : ?module=API&method=VisitsSummary.get&idSite=1&period=year&date=today&format=JSON&token_auth=[TOKEN_AUTH]&segment=actionType==pageviews;dimension1==Academie

This URL also works (note the idSite changed) : ?module=API&method=VisitsSummary.get&idSite=6&period=year&date=today&format=JSON&token_auth=[TOKEN_AUTH]&segment=actionType==pageviews;dimension1==Academie

But this URL doesn’t work (here I specify the 2 sites above at the same time) : ?module=API&method=VisitsSummary.get&idSite=1,6&period=year&date=today&format=JSON&token_auth=[TOKEN_AUTH]&segment=actionType==pageviews;dimension1==Academie

The error I get is “{“result”:“error”,“message”:“Segment ‘dimension1’ is not a supported segment.”}”

I don’t understand why it is working when I specify only one site but not with multiple sites.
Does anyone have an idea ?

Thanks for your help.