If statement and logic

Goal: John Joe(12/2) 

Breakdown:
Name: John.Joe (User picker) 
Birthday: (date&time)

If no name is selected then present "N/A"

What I have tried: 

=if(isnull(pv!processvariable.name), "N/A", user(pv!processvariable.name,"firstName")& " " & user(pv!processVriable.name,"lastName") & "(" pv!processVariable.birthday &" )" )

Problem: Issue with If statement 

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