@Frederike198 there are definitely some syntax issues with your formula.
However, I'm not clear on your app or datasource, so I'll ask - where are Surname and GivenName coming from? Are these variables you've set?
From your data source - you are referring to Title, Surname and GivenName. What is the Title field containing? Is that the Surname? And again, leading back to the last question...is Surname a variable in your app?
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