Hi @ilm
If you want to implement a number increment in the header, then I think you can use the built-in field "PageNumber" to increase the number by increasing the number of pages.
I have added 3 textboxes in the header with their expressions set to:
textbox1: =First(Fields!MATCHESPRIMARY.Value, "DataSet1")+3*(Globals!PageNumber-1)
textbox2: =First(Fields!MATCHESPRIMARY.Value, "DataSet1")+3*(Globals!PageNumber-1)+1
textbox3: =First(Fields!MATCHESPRIMARY.Value, "DataSet1")+3*(Globals!PageNumber-1)+2
Preview:
Best regards,
Aniya