hi we run 2016 enterprise. i picked up an rdl from a peer where she tried the familiar =First(Fields!inv_date.Value, "mydataset") syntax as an expression for atextbox in an ssrs header.
the error that is generated has to do with scope of the dataset etc but i'm aware that textboxes arent associated with datasets, rather matrices etc are.
i also noticed you cant drag a matrix to a header.
so if someone really wants a single dataset column result populating a textbox in a header what do they do? should individual params be populated and then be sourced by text boxes in the hdr?