Why is my formula unparseable?

NBKD

=IFERROR(COLLECT([Completed Date] - [LTP Conversion Date], AND(IFERROR(MONTH(@cell), 0) = Feb84, IFERROR(YEAR(@cell) = 2023, 0)), {CAD Support Type TD}, ="Long Term Project")), "N/A")

The bold is what I want to subtract within the formula.

Paul Newcome

You need either a row number or "@row" reference after the first two cell references, and you have one too many closing parenthesis after "Long Term Project". What exactly are you trying to accomplish with your formula?