Use the Excel IF function with Jet Reports
Overview
You cannot wrap any replicating NL function (Rows, Columns, Sheets) inside of an Excel IF() function. Replicating functions must stand alone in a cell
To make conditional replication work we simply place our IF() function in the Table argument of the replicator and return either the name of the table for which we want to replicate values or an array with one blank value.
This means the replicator will either query a table and replicate its values or return a single blank.
Example
If we wish to list names from the customer table if cell B3=42 our function would look like this:
=NL("Rows",IF($B$3=42,"Customer",{""}),"Name")
If you put an array in the "Table" argument of a replicator it will replicate the values in the array. So, NL("Rows",{1,2,3}) will return the values 1, 2, 3 in rows.